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  • Articles  (532)
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  • Physical Chemistry
  • 1985-1989  (532)
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  • 1
    Electronic Resource
    Electronic Resource
    Relative rates of bromination and chlorination of 4-substituted cyclopentenes in methanol, ethanol and acetic acid (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 26-34 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A set of 4-monosubstituted cyclopentenes, , were synthesized and their relative rates (kX/kH) for bromination and chlorination were determined in methanol, ethanol and acetic acid at 25 °C by competitive method. log(kX/kH) for most of the substituents can be correlated by means of Taft's equation, log(kX/kH) = ρI σI + C. In methanol ρI, Br2 = -2·91, ρI, Cl2 = -0·49, in ethanol ρI, Br2 = -3·07, ρI, Cl2 = -0·70 and in acetic acid ρI, Br2 = -1·64, ρI, Cl2 = -0·65. The presence of C(〈0) is due to a constant steric effect. The deviation of X = H is ascribed to the absence of the steric effect and that of X = CO2Me and CO2Et is accounted for in terms of anchimeric assistance. For chlorination no anchimeric assistance was observed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020104
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the acid-catalyzed hydration of dihydro-1,4-dioxin (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 43-50 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cyclic vinyl ether dihydro-1,4-dioxin is converted to its cyclic hemiacetal hydration product, 2-hydroxy-1,4-dioxane, in aqueous solution by an acid-catalyzed reaction for which kH+ = 1·80 × 10-5 M-1 S-1 at 25°C. This reactivity and the solvent isotope effect kH+/kD+ = 2·2 show that the reaction occurs by rate-determining proton transfer from catalyst to substrate and not by a pre-equilibrium mechanism as recently proposed.2
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020106
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  • 3
    Electronic Resource
    Electronic Resource
    The cation radical vinylcyclobutane rearrangement (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 57-88 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cation radical vinylcyclobutane (VCB) rearrangement is found to be a reaction of substantial scope, synthetic utility, and exceptional kinetic facility. In conjuction with cation radical cyclobutanation, it constitutes an effective method for net (indirect) Diels-Alder addition to electron rich dienophiles. Reactions can be carried out with either aminium salt or photosensitized electron transfer (PET) initiation and are powerfully facilitated by ionizable substituents such as p-anisyl, phenylthio, and phenoxy at the 2-position of the vinylcyclobutane. The intramolecularity of the reaction is clearly established and in four discrete systems preferred sr (suprafacial/retention) stereochemistry is observed. A theoretical basis for sr stereochemistry in the cation radical VCB rearrangement is advanced. The transition state for the reaction is considered to be similar to that for the direct cation radical Diels-Alder cycloaddition, another cation radical pericyclic reaction which converges on the same product. This model of the VCB rearrangement transition state is used to rationalize the strong rate-retarding effect of a Z-methyl substituent attached to the vinyl group and of a methyl substituent at the 4-position of the vinylcyclobutane ring cis to the vinyl substituent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020108
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  • 4
    Electronic Resource
    Electronic Resource
    Multifunctional catalysis for transamination reaction of α-amino acids with glyoxylic acid in synthetic bilayer memberane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 110-116 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The transamination reaction of α-amino acids with glyoxylic acid as catalyzed by copper(II) ions was investigated kinetically in an aqueous medium at pH 5·0 and 30·0°C. L-Phenylalanine transferred its amino group to glyoxylic acid most readily among seven different amino acids used here in the single-walled bilayer vesicle formed with N,N-dihexadecyl-Nα-[6-(trimethylammonio)hexanoyl]-L-histidinamide bromide (N+C5His2C16). Such rate enhancement was found to originate from the cooperative trifunctional catalysis: a coordination effect exercised by copper(II) ions, a general acid-base catalysis by the imidazolyl group of the lipid, and a hydrophobic field effect provided by the bilayer vesicle. Lack of any of the three functions failed to give out significant rate enhancement. As regards correlation between the reactivity and the nature of α-amino acids, the copper(II)-catalyzed transamination was progressively enhanced as hydrophobicity of the α-amino acid was increased in the N+C5His2C16 vesicle.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020204
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  • 5
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020301
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  • 6
    Electronic Resource
    Electronic Resource
    The ‘dimer mechanism’ in aromatic nucleophilic substitution by amines in aprotic solvents (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 1-14 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of aromatic nucleophilic substitutions by amines in protic solvents is well established; on the contrary the mechanism/s of the reactions in aprotic solvents is/are still subject of controversy. The present paper describes several systems for which fourth-order kinetics (third-order in amine) were observed. A mechanism is proposed to account for this as well as other observation such as: overall negative energies of activation, quadratic dependence of kA with non-nucleophilic tertiary bases, spectacular effects of hydrogen-bond donor (HBD) and hydrogen-bond acceptor (HBA) catalysts, etc. Other alternative mechanisms are also discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020102
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  • 7
    Electronic Resource
    Electronic Resource
    Cross interaction constants as a measure of the transition state structure (part III). Mechanism of reactions between 1-phenylethyl benzenesulfonates with N,N-dimethylanilines (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 35-42 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics and mechanisms of the reactions between 1-phenylethyl benzenesulfonates (1-PEB) with N,N-dimethylanilines are investigated in methanol at 35·0°C. Reactivity and selectivity trends were found to be similar to those for the reactions of 1-PEB with anilines, but the magnitudes of cross interaction constants, ρXZ, between substituents X in the nucleophile and Z in the leaving group were substantially smaller indicating no hydrogen-bond bypass bridge formation in the transition state. However, the magnitude of ρXZ suggested a direct electrostatic interaction between the reaction centers in the nucleophile and leaving group in the frontside nucleophilic attack with a loose transition state structure.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020105
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  • 8
    Electronic Resource
    Electronic Resource
    Twisted internal charge transfer emission in B,B-bis(mesityl) pyrroloboranes (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 89-92 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectral characteristics of several simple substituted B,B-bis(mesityl)pyrroloboranes are reported which support a theoretical treatment by Bonacic-Koutecky and Michl (J. Am. Chem. Soc. 107, 1765 (1985)) describing the excited states of simple aminoboranes as an example of twisted internal charge transfer. In the aminoboranes the pyrrolo moiety functions as the electron donor group and the empty p-orbital of the boron atom as the acceptor.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020109
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  • 9
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020201
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  • 10
    Electronic Resource
    Electronic Resource
    Reassignment of the fundamental vibrations of azetidine from ab initio calculations (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 183-186 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The harmonic vibrational frequencies were calculated analytically at the 6-31** level for azetidine using the GAUSSIAN 82 program. The results strongly indicate the presence of several errors in a recent assignment of the fundamentals of azetidine based on a normal coordinate analysis and a revised assignment is suggested. It is concluded that reliable vibrational data for azetidine in the gas phase are needed in order to resolve the remaining ambiguities in the interpretation of the spectra.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020210
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  • 11
    Electronic Resource
    Electronic Resource
    Mechanism of the Grignard reaction (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 205-213 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanism of the Grignard reactions of aromatic ketones in THF was studied by spectroscopic and kinetic methods. The stable radical intermediates generated in the initial electron transfer from Grignard reagent to ketones are in a state of aggregated dimer of corresponding ion-radical pairs; in which two ketone anion radicals are bridged by a dimer di-cation of Grignard reagent. Subsequent alkyl radical transfer from dimeric Grignard reagent cation moiety to ketone anion radical aggregated each other are promoted by a participation of another neutral Grignard reagent. Proposed mechanism by present authors is able to explain well addition products/reduction products ratios in the Grignard reactions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020303
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  • 12
    Electronic Resource
    Electronic Resource
    Non-hierarchical classification of organic solvents using characteristic vector analysis of physical and empirical solvent parameters (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 232-242 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characteristic vector analysis of a set of six physical and empirical parameters of 103 commonly used organic solvents (bp, ∊r, μ, nD, ETN, and δ) gives four vectors describing 95% of the total data variability. Non-hierarchical cluster analysis, applied to our results, leads to ten separate classes of organic solvents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020306
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  • 13
    Electronic Resource
    Electronic Resource
    A preliminary quantum-chemical study of the mechanisms for the reactions of perchlorofluoroethanes with nucleophiles initiated by chlorophilic attacks (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 103-109 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A preliminary theoretical study of the mechanisms for the reactions of the perchlorofluoroethanes CF2ClCCl3 (1), CF2ClCCl2F (2) and CF3CCl3 (3), with nucleophiles has been carried out by the MNDO method, following the experimentally suggested process shown in Scheme 1. The unlikely chlorophilic attack in the first step of Scheme 1 has been shown to be feasible for 1, 2 and 3 by analysis of the MO interactions. The second step has been found to be affected by the anionic hyperconjugation which stabilizes the anions CF2ClCCl2- (4), CF2ClCClF- (5) and CF3CCl2- (6) and would make reactions (2) (the second step) unfeasible in gas phase, but in solution reaction (2) may still easily occur for 4 and 5.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020203
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  • 14
    Electronic Resource
    Electronic Resource
    Studies on organophosphorus compounds XXXII. A molecular mechanics study of the hydrolytic reaction of alkylphosphonates and alkylphosphonyl chlorides (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 146-160 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The alkaline hydrolysis of several alkylphosphonates and alkylphosphonyl chlorides has been investigated by molecular mechanics calculations (MM2, 1985 version). The difference of the steric energies (ΔE) between tetracoordinate substrate and pentacoordinate transition state of phosphorus compounds represents the activation energy (ΔE≠) in hydrolysis. The change of ΔE for various alkyl groups relative to methyl group (ΔΔER) is suggested as a measure of the steric effect of substituents. Thus the correlation analysis involving log k and ΔΔER of the branched alkyl group gives good results and it is reasonable to anticipate that analogous treatment using ΔΔER for the straight chain alkyl group is not satisfactory owing to the minor contribution of steric effect of the latter. However, the multiple regression analysis of log k with ΔΔER and Taft's σ* provides very good results. As shown by us, for the hydrolytic reactions studied, the proposed ΔΔER is much better than Taft's Es and Charton's ν, the commonly used well-known steric parameters in the chemistry of carbon compounds.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020207
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  • 15
    Electronic Resource
    Electronic Resource
    Theoretical studies of the singlet and triplet potential energy surfaces of cyclobutanediyl (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 161-176 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cyclobutanediyl (2) has been studied in both its singlet and triplet states by ab initio electronic structure theory. The triplet, which is the ground state of the molecule, exists in both C2h and C2v forms which interconvert via a Cs transition state. For the singlet, only a C2h form is found. It passes, via a Cs transition state, onto the C2v surface on which bicyclobutane (3) is the only minimum. The ring-flipping (inversion) process in 3 includes the singlet biradical as an intermediate, and involves a novel, non-least motion path similar to one previously proposed by Gassman. Semiclassical periodic orbit theory indicates that the various minima on both the singlet and triplet surfaces can interconvert via quantum mechanical tunneling.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020208
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  • 16
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020101
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  • 17
    Electronic Resource
    Electronic Resource
    Ion pairs in solvolysis reactions. Kinetic deuterium isotope effects for deprotonation of carbocation intermediates in aqueous solvent (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 15-25 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolysis of 2-X-2-phenylpropane (1-X) in 25 vol% acetonitrile in water at 25°C produces 2-hydroxy-2-phenylpropane (1-OH) and 2-phenylpropene (3). The carbocationic intermediate discriminates between different nucleophiles; azide anion, acetate anion, and methanol are more efficient nucleophiles than water, kN3/kH2O = 42 kOAc/kH2O = 3, and kMeOH/kH2O = 2·9 (ratio of second-order rate constants). The fraction of the elimination product 3 increases with increasing basicity of the leaving group X as well as by addition of general bases. The Brønsted parameter for this catalysis is small, β = 0·13, with substituted acetate anions. The kinetic deuterium isotope effect for the dehydronation of the intermediate has been measured (assuming the reaction from intermediate to alcohol is insensitive to isotopic substitution) employing the hexadeuterated substrate d6-1-X as k3H/k3d6 = 3·5 ± 0·2 for the chloride 1-Cl with acetate anion, and, without added base, 3·1 ± 0·2 for the acetate 1-OAc, and 3·1 ± 0·2 for the p-nitrobnzoate 1-PNB, respectively, and ∼5 for the protonated methyl ether 1-OMeH+. The variation in isotope effect with change in leaving group is discussed in terms of elimination from contact ion pairs and ‘free’ carbocation. The overall kinetic isotope effect for the solvolysis was found to be kobsH/kobsd6 = 1·31 (1-OMeH+), 1·38 (1-OAc), 1·40 (1-PNB), and 5·7 (1-OH2+). These isotope effects consist of the isotope effect k12H/k12d6 for the formation of the substitution product 1-OH and k13H/k13d6 for production of the olefin 3. It is concluded that the latter isotope effect is enlarged owing to a branched mechanism in which the deprotonation of the carbocationic intermediate competes with formation of the substitution product. As large an isotope effect as k13H/k13d6 ∼6·5 has been measured for 1-OMeH+.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020103
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  • 18
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    The use of IR spectroscopy to monitor the conversion of matrix isolated phenylacetyl chloride to phenylacetyl cation, without decarbonylation to benzyl cation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 51-56 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: IR spectroscopy is presented as a convenient means to monitor the formation of acyl (and alkyl) cations from corresponding acid chlorides, with Lewis acids at low temperature in the solid state. Phenylacetyl chloride is co-deposited (under vacuum at -173°C with antimony pentafluoride on a KBr window), as in the ‘molecular beam’ method of cation generation. The initial IR spectrum of the deposition shows (in addition to starting materials) that a small amount of phenylacetyl cation (2274 cm-1) has been formed. Warming the solid matrix to -123°C Promotes the smooth conversion of acid chloride to acyl cation. Ultraviolet irradiation (through quartz windows) at -123°C to -73°C facilitates this conversion but does not result in the loss of carbon monoxide from the acyl cation to form benzyl cation. When benzyl chloride is used in place of phenylacetyl chloride, there is no noticeable difference between IR spectra taken before and after warming and/or photolysis of the solid deposition.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020107
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  • 19
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    Selective 1,2-addition of organocerium(III) reagents to α,β-unsaturated carbonyl compounds (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 93-102 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Organocerium(III) reagents reacted with α,β-unsaturated carbonyl compounds to give 1, 2-addition products (allylic alcohols) in good to high yields. The reaction was studied from a mechanistic point of view by the use of (E)- and (Z)-1-(4′-methoxyphenyl)-3-phenyl-2-propen-1-ones and 4,4-ethylenedioxy-2,6-dimethyl-2,5-cyclohexadienone as the probe compounds. A polar pathway was suggested for the reaction with the former enones. On the other hand, the operability of single electron transfer processes was demonstrated in the reaction with the latter probe compound.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020202
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  • 20
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    Formation of 1:1 adducts between bis(1,2-diaryl-1,2-ethylenedithiolato)metal(0) (metal = NI, PD, and PT) and quadricyclane and their photodissociation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 131-145 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bis(1,2-diaryl-1,2-ethylenedithiolato)metal(0) complexes (1; metal = Ni, Pd, and Pt) react with quadricyclane (Q) to give selectively 1:1 adducts which are identical with the adducts between 1 and norbornadiene (NBD). In the adducts, two sulfur atoms of the different dithiolato ligands are added to one of the double bonds of NBD. The reactions of 1 with Q are 103-104 times faster than those with NBD. The more electropositive dithiolatometal complexes react faster with Q and NBD. The adducts are dissociated to the free dithiolatometal complexes and NBD by UV-irradiation (254-436 nm). Upon irradiation with 254 nm light, the photodissociation occurs before the decomposition of the dithiolatometal complexes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020206
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  • 21
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    Gas phase reactivities of isomeric ions: Methylenediphenylcyclopropane and diphenylmethylenecyclopropane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 117-130 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gas phase ion/molecule reactions have been used to probe the structure of ions obtained by electron impact upon 1-(diphenylmethylene)cyclopropane and 2,2-diphenyl-1-methylenecyclopropane. The resulting ions of molecular composition C16H14 (m/z 206+) were reacted with charge transfer reagents (6·9 〈 IP 〈 8·8eV), giving evidence for the presence of isomeric ions with different reactivities. The less reactive ion is identified as a trimethylenemethane species (TMM+) in which one cyclopropane bond is broken; the more reactive ions are assigned as vertical ions in which the cyclopropane ring is unaffected. The vertical ions have recombination energies of 8·44 ± 0·05eV, whereas TMM+ has one of 7·41±0·05eV. The TMM+ fraction is not constant; it increases with increasing IP of the reagent. This is attributed to a reagent-catalyzed isomerization of the vertical ion to TMM+. In addition, the reagent ions are observed to undergo a unique reaction with the neutral methylenecyclopropane derivatives: electron transfer and ring opening to yield TMM+. These findings limit the application of the customary equilibrium measurements as a method to determine the substrate IP.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020205
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  • 22
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    General base catalysis of photo-smiles rearrangement of 1-(4-nitrophenoxy)-2-anilinoethane in aqueous solution. Identity of the proton-donating intermediate (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 177-182 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 4-O2NC6H4OCH2CH2NHPh undergoes clean base-catalyzed Smiles photorearrangement to 4-O2NC6H4N(Ph)CH2CH2OH in dimethyl sulfoxide-water (25:75). A linear plot of φ-1 vs [OH-]-1 indicated that the limiting quantum yield at high [OH-] is 0·12 and that uncatalyzed photorearrangement does not occur. Rate constants for the deprotonation step were determined for a variety of bases having conjugate acid pKa values in the range 5-10. When plotted according to the Brønsted Catalysis Law, these data gave a non-linear plot approaching slopes of zero and unity above and below a pKa of 6-7. This indicates that the proton-donating intermediate in this photo-Smiles rearrangement is the zwitterion diradical (pKa ≈ 7) rather than the Meisenheimer complex (pKa ≈ 2).
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    Theoretical study of pyrazole elimination of N-alkyl pyrazoles (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 225-231 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas-phase pyrazole elimination of N-alkyl pyrazoles has been studied using MNDO semi-empirical molecular orbital (MO) theory with complete geometry optimization of all stationary points. We found that the activation energies (Ea) of the concerted processes are around 80 kcal/mol, 25 Kcal/mol higher than experimental values. But the differences in Ea between compounds with different substituents are in good agreement with the experimental ones.
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    Photostimulated reactions of neopentyl halides with nucleophiles by the SRN1 mechanism (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 255-262 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photostimulated reaction of neopentyl halides with different nucleophiles by the SRN1 mechanism of nucleophilic substitution has been studied. Neopentyl halides do not react with carbon nucleophiles, diethylphosphite, diphenylphosphonite and azide ions, but they react with arsenide and selenide ions. The photostimulated reaction of neopentyl bromide with diphenylarsenide ions gave only the straightforward substitution product neopentyldiphenylarsine. On the other hand, the photostimulated reaction of bromobenzene with dineopentyl arsenide ions gave three arsines: dineopentylphenylarsine, neopentyldiphenylarsine and triphenylarsine. Neopentyl chloride reacts under irradiation with diphenylphosphide ions giving good yields of the substitution product.
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    URL: http://dx.doi.org/10.1002/poc.610020401
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    Crystal and molecular structures of dimesitylketene and bis(3,5-dibromo-2,4,6-trimethylphenyl)ketene. Intrinsic torsional angles and buttressing effects in 1,1-dimesitylvinyl propellers (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 271-280 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal and molecular structures of dimesitylketene (1) and bis(3,5-dibromo-2,4,6-trimethylphenyl)ketene (2), the first free ketenes to be studied by X-ray diffraction, have been determined. The molecules of 1 and 2 have crystallographic C1 and C2 symmetry, respectively, and exist in a propeller conformation. Molecular mechanics calculations of 1 and 2 using a modification of Allinger's new allene parameters reproduce satisfactorily the structural parameters of the ketenes. The torsional angles of the aryl rings in 1 and 2 are similar (ca. 50°) and are regarded as ‘intrinsic’ values for a 1,1-dimesitylvinyl propeller. From the similarity in aryl torsional angles in 1 and 2 it is concluded that the buttressing effects in 2 (if any) are not markedly manifested in the structural parameters of 2.
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    Laser flash photolysis of a chromium carbene complex: Pentacarbonyl(1,3-dimethyl-4-imidazolin-2-ylidene)chromium(0) (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 323-330 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photoreactions of Cr(CO)5(Im) (Im = 1,3-dimethyl-4-imidazolin-2-ylidene) have been investigated by laser flash and continuous photolysis. Quantum yields for the disappearance of Cr(CO)5(Im) in benzene under Ar or CO were very low, although transients observed by laser flash photolysis reacted rapidly with CO. This suggests that photodissociation of the carbene ligand is very minor. The laser flash photolysis at 337 nm in benzene (B) gave a transient (λmax = 630 nm), which converted to the second transient (λmax = 455 nm) within ∼100 ns. The kinetic studies of these transients revealed that the first one is a ‘free’ coordinatively unsaturated species (Cr(CO)4(Im)) and the second one carries a solvent molecule as a ligand (Cr(CO)4(Im)(B)). From the comparison of Cr(CO)4(Im) and Cr(CO)5, apparently lower reactivity of Cr(CO)5 was found to be due to the strong coordination of a solvent molecule. The Im ligand neutralizes the deficit of electron density on Cr. A simple synthesis of Cr(CO)5(Im) was also described.
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    A mechanistic study of the selenium-catalysed carbonylation of secondary amines with carbon monoxide (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 359-362 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction pathway of urea formation by selenium-catalysed carbonylation of secondary amines with carbon monoxide in the presence of oxygen was studied using piperidine as a secondary amine. It was established that selenium reacts with carbon monoxide and piperidine to give carbamoselenoate as an intermediate, which affords biscarbamoyl diselenide by the oxidation with molecular oxygen. Aminolysis of biscarbamoyl diselenide gives the urea derivative, accompanying the regeneration of selenium catalyst.
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    Alkylating properties of phosphate esters. 4. Medium effects on methylation of pyridines by trimethyl phosphate (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 377-382 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The rates of N-methylation of pyridine and its ring-substituted derivatives by trimethyl phosphate were measured in D2O and in CDCl3. Relative rates, together with the solvent activity coefficients of substrates for the transfer form chloroform to water, were used for determining the solvent activity coefficients of the activated complexes for this SN2 reaction. The results indicate early activated complexes for all pyridines, with the most nucleophilic substrate showing the most reactant-like activated complex.
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    Experimental determination of carbon vs. oxygen regioselectivity in reactions of gas-phase enolate ions (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 389-409 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A gas-phase experimental investigation of the competition between carbon and oxygen alkylation of a series of cyclic and acyclic enolate ions is described. Perfluoropropylene is shown to react in a characteristic way with oxyanions and carbanions to produce distinctive ionic products. The relative yields of these products formed in reactions with ambident enolate ions provides a measure of their intrinsic carbon vs. oxygen regioselectivity. The results for a series of enolates derived from aldehydes, ketones, esters, amides and related compounds show a wide range of reactivity which is a function of the nature of the central substituent. Most aldehyde and ketone enolates react mainly through oxygen, while enolates with σ-acceptor of π-donor type central substituents react mainly thorugh carbon. Ring-size in cyclic ketone enolates also influences C vs. O regioselectivity, i.e. small-ring enolates react mainly through carbon, while larger ring enolates (C7-C9) react preferentially through oxygen. The enolate reactivity patterns can be generally accounted for by the keto-enol energy differences for the parent carbonyl compounds, although some exceptions are evident. The origins of the highly variable, kinetically determined regioselectivities are discussed.
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    ESCA studies of carbanionic compounds: Butyllithium in heptane solution and dibutylmercury in the gas phase (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 417-424 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two organometallic reagents, butyllithium in heptane solution and dibutylmercury in the gas phase, have been studied by means of core electron spectroscopy. The property of particular interest was the charge polarization as reflected by the ESCA shifts. In the butyllithium compound the C1s binding energy is shifted to a lower value by 1·8 eV for C-1 (situated closest to the Li+ ion) relative to the heptane solvent carbon. This is due to the anionic character of the C-1. The interpretation of the experiments was supported by comparing the results with ab initio calculations made on geometry-optimized butyllithium, butyl anion and butane.
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    Dynamic isotope dilution kinetic study of the thermal conversions of bicyclo[3.2.0]hept-2-ene to bicyclo[2.2.1]hept-2-ene and to cyclopentadiene and ethene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 455-466 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Mixtures of bicyclo[3.2.0]hept-2-ene and bicyclo[2.2.1]hept-2-ene, with one isomer labeled with two deuterium atoms, were isomerized in the gas phase at 276 °C. By following the concentration ratios of d0 and d2 versions of bicyclo[2.2.1]hept-2-ene as functions of time one finds that the partitioning of bicyclo[3.2.0]hept-2-ene between the primary products bicyclo[2.2.1]hept-2-ene and cyclopentadiene plus ethene is 2:1. This and earlier stereochemical results permit the calculation of the partitioning of the [3.2.0] olefin between the orbital symmetry allowed [1,3] carbon shift-with-inversion product and several forbidden or non-concerted reaction channels (approximately 1:1) and the stereochemistry of the ethene d2 formed from exo,exo-[6,7-2H2]bicyclo[3.2.0]hept-2-ene directly (1:1 E: Z).
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    URL: http://dx.doi.org/10.1002/poc.610020701
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    Reflections on the π-complex theory of benzidine rearrangementsDedicated, with respect, for the 70th birthday of Professor Michael Dewar, who, on scribbled, lunch-time table napkins at the 1961 American Chemical Society meeting in Chicago tried but (fortunately) failed to convince me of the validity of his π-complex theory. I wish I had kept the napkins. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 491-506 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ups and downs, and reasons therein, of the π-complex theory of the mechanism of the benzidine rearrangements, and the possible role of π-complexes in a newer understanding of the rearrangements, are described.
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    Hydrogen-bonding. Part 4. An analysis of solute hydrogen-bond basicity, in terms of complexation constants (log K), using F1 and F2 factors, the principal components of different kinds of basicityPart 3. M. H. Abraham, P. P. Duce, D. V. Prior, R. A. Schulz, J. J. Morris and P. J. Taylor, J. Chem. Soc. Faraday Trans. 1, 84, 865 (1988). (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 243-254 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The principal components factors F1 and F2 in the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log K = {\rm BDP}_0 + S_1 F_1 + S_2 F_2 $$\end{document} have been used to obtain S1 and S2 values for sets of hydrogen-bond bases against 32 reference acid/solvent systems. The constants S1 and S2 define an angle θ = tan-1 S2/S1 that is a measure of the electrostatic:covalent bonding ratio in the hydrogen-bond complex. It is shown that θ can vary from 53 (4-fluorophenol in CH2Cl2)to 86 degrees (Ph2NH in CCl4) depending on the reference acid and solvent. This variation in θ can lead to family dependent behaviour in plots of log K for bases against a given reference acid system vs log K for bases against another reference acid system, and precludes the construction of any general scale of hydrogen-bond basicity using log K values. Amongst a quite wide range of reference acid/solvent systems θ varies only from 64 to 73 degrees, and for bases against these reference systems a ‘reasonably general’ scale could be set up. Such a scale could be extended to bases against reference acid/solvent systems outside the 64-73 degree range provided that certain classes of base (e.g. pyridines, alkylamines) were excluded from the additional reference acid/solvent systems.
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    Application of Marcus theory to photochemical proton transfer reactions. II. Modifications based on intersecting state models (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 300-322 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various modifications of the Marcus equation have been applied to the problem of photochemical proton transfer, using available data on general acid-catalyzed photohydration reactions. These include incorporation of asymmetry and tightness parameters, as well as distance variation as a function of exoor endothermicity. The intersecting state model of Formosinho has also been successfully applied to these reactions. The overall conclusion from all of these approaches is that the reactions are characterized by somewhat asymmetric and ‘loose’ transition states, with a small but significant degree of charge development on the in-flight proton at the transition state. Estimates of the intrinsic barriers and work terms place these in the 5-7 kcal and 2-3 kcal ranges respectively. A simple valence bond configuration mixing model leads to similar qualitative conclusions about the nature of the transition states in these reactions.
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    A theoretical and experimental investigation of acid catalyzed rearrangements of small [n]cyclophanes (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 331-348 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The difference in reactivity of small [n]cyclophanes towards CF3CO2H is discussed in terms of charge densities, strain energies and proton affinities. These data are calculated with MNDO and MINDO/3 for para-, meta- and ortho-cyclophanes and for their ipso-protonation products; an attempt is made to transform gas phase ΔHf0 values into liquid phase ΔH0f values. Experimental evidence is presented that the acid catalyzed rearrangement of [5]paracyclophane to its ortho-isomer proceeds via two consecutive 1,2-carbon shifts without deprotonation; intermediate adducts were identified by NMR-spectroscopy. Thus, a gradual shift in reaction pattern in the series [4]-, [5]- and [6]paracyclophane is observed experimentally, in line with the calculational results.
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    URL: http://dx.doi.org/10.1002/poc.610020501
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    Free-radical reactions of cyclic ethers and sulfides with bromotrichloromethane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 367-376 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The relative rates of hydrogen atom abstraction from a series of twelve saturated cyclic ethers and sulfides were determined at 70°C. The abstracting radical could be generated from bromotrichloromethane both photolytically or by the thermal decomposition of AIBN. The reaction rates did not show a dependence upon method of radical generation. Reaction occurred only at the position adjacent to the heteroatom. The reactivity of the cyclic ethers was in the order C4H8O 〉 C6H12O 〉 C3H6O 〉 C5H10O. This trend would indicate appreciable influence by ring strain, however, the slightly greater reactivity of tetrahydrofuran relative to oxepane suggests a contribution by stereoelectronic factors as well. The reactivity of the cyclic sulfides, which reacted faster than the corresponding ethers, was in the order C4H8S 〉 C5H10S 〉 C6H12S. This would imply little influence of ring strain. The major structural effect would be that of variable electron donating ability of the sulfur atom. The rate of reaction of thietane was also determined. It was found to preferentially undergo SH2 attack at the sulfur atom followed by ring opening rather than hydrogen abstraction. The reactivities of both series of compounds were decreased by the inductive effect of a second heteroatom beta to the reaciton site.
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    Group transfers 4. Arylselenide aniondiaryl diselenide exchange (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 410-416 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Barriers for group transfers between nucleophiles have been postulated to be lowered when the transferring group can carry a considerable negative charge. Furthermore, anions readily subject to one electron oxidation appear to lead to lower barriers than do those of high oxidation potential. These suggestions are pursued here on the identity reaction ArSe- + ArSeSeAr → ArSeSeAr + ArSe-. Indeed the reaction is very fast, as shown by the appearance of only a single peak in the 77Se-NMR in an acetonitrile solution containing both ArSeNa and ArSeSeAr. The rate constant can be only very roughly estimated at low temperatures and dilute solutions, and is likely diffusion controlled for Ar = phenyl and p-methoxyphenyl. A stable intermediate (ArSe)3-, analogous to Br3-, is indicated, but quantitative stability could not be determined, from either the NMR or the UV spectra. Some properties of 77Se-NMR are discussed.
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    Lack of protonation of benzene and toluene by trifluoromethanesulfonic acid and its significance for evaluating superacid strengths (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 425-427 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Distribution between pentane and trifluoromethanesulfonic acid (TFMSA) and carbon-13 NMR measurements showed that benzene and toluene are not protonated to any significant extent in TFMSA. This finding contradicts previous reports, and validates the ranking of superacids based on the extent of benzene protonation.
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    Bifunctionally catalyzed 1,3-proton transfer of a propene by a sec-amidine studied by deuterium isotope effects. A stepwise two-proton transfer mechanism (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 429-447 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A two-hydron transfer mechanism involving hydron transfers from carbon to nitrogen and from nitrogen to carbon was studied. The rearrangement of 1,3,3-triphenylpropene (1) into 1,1,3-triphenylpropene (2) catalyzed by 2,10-diazabicyclo[4.4.0]dec-1-ene (3) in benzene at 25·00°C was studied by 2H-labeling experiments and kinetic 2H-isotope effects. The synthesis and purification of [6,10-2H2]-2,10-diazabicyclo[4.4.0]dec-1-ene ([6,10-2H2]-3), [3-2H]-1,3,3-triphenylpropene ([3-2H]-1), [3-2H]-1,1,3-triphenylpropene ([3-2H]-2) and [3,3-2H2]-1,1,3-triphenylpropene ([3,3-2H2]-2) together with their precursors are reported. Partial reaction of [3-2H]-1 with [6,10-1H2]-3 gave 42% conversion into product 2, which was shown by 1H NMR to be composed of 88% [3-1H]-2 and 12% [3-2H]-2. Partial reaction of [3-1H]-1 with [6,10-2H2]-3 gave 43% of 2, composed of 73% [3-1H]-2 and 27% [3-2H]-2.These results clearly show that a substantial fraction of the reaction takes place in a bifunctional manner but isotope exchange and/or monofunctionally catalyzed reactions interfere. The following kinetic deuterium isotope effects on the rearrangement 1 → 2 were measured: kHH/kDH = 6·56; kHH/kHD = 1·19; kHH/kDD = 7·08; kHD/kDD = 5·94; and kDH/kDD = 1·08.On the basis of these results, a concerted two-hydron transfer mechanism is excluded. Instead, a stepwise mechanism is favored, in which at first the 3-hydron of 1 is abstracted by 3 yielding an ion pair(s), the carbanion of which in a separate step is then hydronated to yield the product 2.The abstraction of the 3-hydron from 1 might be hydrogen bond assisted. The two hydron transfer transition states are together rate limiting, although they limit the rate to different extents. A detailed mechanistic analysis is presented together with the results of an investigation of the nature of the catalyst. The dimerization constant for 3 was determined by 1H NMR to be 1·67 l mol-1 at 25·0°C. Isotopomer composition was measured by 1H NMR and GLC was used for the separation of the substrate and products. Computer-assisted capillary GLC was used for the kinetics.
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    Cross-interaction constants as a measure of the transition state structure (part V).For Part IV, see ref. 3. The transistion state structure for reactions of phenacyl benzenesulphonates with benzylamines in methanol (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 484-490 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The Kinetics of reactions of phenacyl benzenesulphonates with benzylamines were investigated in methanol at 45·0 °C and the cross-interaction constants λXY, λYZ and βXZ were determined in order to elucidate the transition-state structure. The unusually small magnitude of λXY can only be accounted for by the resonance ‘shunt’ effect of the α-CO group of the phenacyl system. Large |λYZ| values indicate a small degree of bond breaking whereas relatively large |βXZ| values compared with those for the dissociative SN2 reaction indicate a relatively tight transition state for the reactions. Further, the similar magnitudes of βXZ values compared with those of the corresponding aniline nucleophile series suggest a similar transition-state structure for the two armatic amine nucleophile series.
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    Amines as leaving groups in nucleophilic aromatic substitution reactions. II.For Part 1, see Reference 1. Hydrolysis of N-(2,4,6-trinitrophenyl)amines (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 507-518 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrolysis reactions of N-(2,4,6-trinitrophenyl)piperidine (2) and N-(2,4,6-trinitrophenyl)-morpholine (3) were studied. Two kinetic processes well separated in time are observed in both reactions. The fastest process, which is reversible, leads to the formation of a species of λmax 260 and 410 nm and is attributed to the formation of a σ complex of stoichiometry 1 : 2 due to the addition of a second HO- to the σ complex of 1 : 1 stoichiometry. The slowest process leads quantitatively to picrate ion. The equilibrium constants for the formation of the σ complexes of 1:1 and 1:2 stoichiometries and the rate of formation and decomposition of the latter complex were determined. The kinetic data for the slow process lead to the conclusion that the picrate ion is formed from the attack of HO- on the two σ complexes, confirming previous findings. There are some differences in the calculated rates for 2 and 3 which may be an indication that the elimination of the amine is partially rate determining.
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    Decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion in cationic micelles: Effect of head group size (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 553-558 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The rate of decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion increases sharply with increasing head group size in a series of cetyltrialkylammonium bromides (C16H33NR3Br: R = Me, CTABr; R = Et, CTEABr; R = n - Pr, CTPABr; R = n - Bu, CTBABr) with rate enhancements of 102 (CTABr) and 2·8 × 103 (CTBABr). Micellized tetradecylquinuclidinium bromide and hexadecyl-N-methylmorpholinium bromide are slightly better catalysts than CTABr, as is 1,3-bis(N-cetyl-N,N-dimethylamino)propane dibromide, but p-octyloxybenzyltrialkylammonium bromides (alkyl = Me, n - Bu) are less effective than the corresponding CTA+ surfactants. These differences in catalytic efficiency depend on the head group structure and the extent to which the cationic head groups become less accessible to water rather than the overall micellar structure.
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    Thermodynamic and spectroscopic properties of 2-pyrrolidinones. 3.For Part 2, see P. Ruostesuo and P. Pirilä-Honkanen, submitted for publication, J. Sol. Chem. NMR spectroscopic studies on 2-pyrrolidinone in different solvents (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 565-572 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: 1H, 13C, 15N and 17O NMR chemical shifts, 1JNH and 1JCH coupling constants and line widths (Δν1/2) of the 14N and 17O resonance lines were determined for 2-pyrrolidinone neat and for several 2-pyrrolidinone-solvent systems. The 17O NMR chemical shift of 2-pyrrolidinone was clearly most sensitive to the solvent effects, but changes with the solvent were also observable in the 13C (C=O) and 15N NMR chemical shifts, the 1JNH coupling constants and especially the line widths of the 14N and 17O resonance lines. In general, the results reflected a hydrogen bonding effect between the oxygen atom of 2-pyrrolidinone and the proton-donating solvents and a weak molecular interaction of the NH proton of 2-pyrrolidinone with the proton-accepting solvents. The results are compared with the NMR data for the corresponding binary mixtures of 1-ethyl-2-pyrrolidinone.
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    Anionic nucleophile-cation radical combination reactions. The super-electrophilic properties of cation radicals in solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 580-584 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Rate constants were determined for the combination reactions of a series of cation radicals derived from substituted anthracenes with acetate, p-nitrobenzoate, trifluoroacetate, nitrate and perchlorate ions. Rate constants, depending on the identities of the cation radicals and the nucleophiles, ranging from about 200 to 2 × 1010 1 mol-1 s-1 were observed in acetonitrile at 293 K. The key steps in the reaction are (1) reversible complex formation between the anion and the cation radical followed by (2) irreversible bond formation \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\rm{Ar}^{ + \cdot } + \rm{X}^ - \rightleftharpoons {{\rm{Ar}^{ + \cdot } } \mathord{\left/ {\vphantom {{\rm{Ar}^{ + \cdot } } {\rm{X}^ - }}} \right. \kern-\nulldelimiterspace} {\rm{X}^ - }}} &&&&& {(1)} \\ {{{\rm{Ar}^{ + \cdot } } \mathord{\left/ {\vphantom {{\rm{Ar}^{ + \cdot } } {\rm{X}^ - }}} \right. \kern-\nulldelimiterspace} {\rm{X}^ - }} \to \rm{Ar}^ \cdot - \rm{X}} &&&&& {(2)} \\ \end{array} $$\end{document}.The preliminary results show that cation radical-anionic nucleophile reactions can be very facile. The cation radicals of 9-nitro- and 9-cyanoanthracene are particularly reactive, giving rise to rate constants close to the diffusion-controlled limit with all anionic nucleophile studied and even react moderately rapidly with perchlorate ion. The reaction with perchlorate ion can be compared to the behavior of stable carbenium ions that coexist with the anion in solution and in crystalline salts.
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    Analysis of solvent effect on SN2 reactions by different theoretical models (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 611-622 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The solvent effect on two SN2 reactions was evaluated by discrete, continuum and discrete-continuum models. The potential energy profiles were found to change dramatically on introduction of the solvent effect. The double-well shape which characterizes the F- + CH3F → FCH3 + F- reaction in the gas phase becomes unimodal when the solvent is introduced, in good agreement with experimental data. The solvation parameters are found to intervene in the reaction coordinate. Recent Monte Carlo and molecular dynamics calculations are discussed.
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    Comparative kinetic study of solvent effects in the reactions of 1,2-dinitrobenzene with butylamine and piperidine (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 631-645 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The kinetics of the aromatic nucleophilic substitution (SNAr) reactions of 1,2-dinitrobenzene (1,2-DNB) with butylamine (BA) and piperidine (PIP) were investigated as a function of the amine concentration and temperature, in chloroform, ethyl acetate, tetrahydrofuran (THF), acetonitrile (ACN), dimethylformamide (DMF), dimethyl sulphoxide (DMSO). benzene, toluene, chlorobenzene and diisopropyl ether.In the set of solvents consisting of ethyl acetate, THF, ACN, DMF and DMSO, neither reaction is catalysed (kA = k1). The sequence and range of reactivity for BA and PIP are similar in these solvents. These results indicate that reactions in which nitro in the leaving group behave differently from SNAr reactions with other leaving groups, such as halogens or alkoxy groups, since an intramolecular hydrogen bond may be expected between the leaving nitro group and the ammonium H of the nucleophiles. The correlations of the rate coefficients obtained with Taft and Kamlet's solvatochromic method support these conclusions.On the other hand, these reactions show mild acceleration with relatively non-polar solvents such as the aromatics and diisopropyl ether. The donor properties of these solvents and experiments with solvent mixtures suggest the formation of electron donor-acceptor complexes between them and 1,2-DNB. Hence the preferential solvation of 1,2-DNB by the donor solvent accounts for the mechanism observed.
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    Theoretical studies on the hydrolysis of urea in acid solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 281-299 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Mechanisms of the hydrolysis of urea have been investigated using the MNDO and AMI methods. All geometries were fully optimized and the transition states were characterized by calculating force constants. The results showed that: (i) The unimolecular decomposition process via the direct intramolecular proton transfer is preferred to both the A1 and the bimolecular nucleophilic attack by water, in agreement with the experimental results of Shaw et al. in the low acidity medium. (ii) The diprotonated form of urea exists as an equilibrium species, which undergoes the A2 type hydrolysis more favorably than the monoprotonated form, as Moodie et al. found in the intermediate acidity medium. (iii) The A2 hydrolysis of the monoprotonated form is very similar to those of acetamide and methyl carbamate. (iv) As the number of the solvate water molecules increases, the activation barrier for the A2 process of the monoprotonated form increases while that for the unimolecular decomposition of the free base form decreases, indicating a possibility of the barrier height reversal in the bulk solvent in favor of the latter process, thus accommodating all the experimentally found trends in the urea hydrolysis. The A1 mechanisms involving six-membered ring type intermediates can be ruled out as untenable since no such equilibrium species was obtained by both the MNDO and AM1 calculations.
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    Lack of manifestation of an anomeric effect in 2-diphenylphosphinoyl-1, 3-dioxane and 2-diphenylphosphinoyl-1, 3-oxathiane1Dedicated to Prof. Xorge A. Domínguez, Tecnológico de Monterrey, on the occasion of his 60th birthday. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 349-358 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The spectroscopic evidence for the predominance of the equatorial conformers in the title compounds was confirmed by the study of derivatives containing counterpoise substituents, and by chemical equilibration of anancomeric models. ΔG27o°C [P(O)Ph2] ≳ 3·2 kcal/mol was determined in the dioxane, and ΔG55o°C [P(O)Ph2] = 1·42 ± 0·12 kcal/mol in the oxathiane. It follows then that the strong anomeric interaction observed previously in S—C—P segments does not show up in the six-membered heterocycles 2 and 7, which contain O—C—P moieties. This may be due to an inherent inability of oxygen to act as an electron donor to the axial P(O)Ph2 substituent, or to a dominant repulsive steric interaction in the axial conformers.
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    Oxygen-17 NMR study on substituted α, α, α-trifluoroacetophenonesPart VI of Nuclear Magnetic Resonance Studies. For Part V, see. K.-T. Liu, Tetrahedron Lett. 1207-1208 (1977). (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 363-366 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: An excellent linear correlation of oxygen-17 substituent chemical shifts (SCS) for twelve α, α, α-trifluoroacetophenones with single σ+ constants, δ = 24·6σ+ + 556·3 (correlation coefficient 0·998) has been observed. However, from this plot, an SCS of 34·3 ppm for 1,1,1-trifluoroacetone will give a corresponding σ+ (γ+) value of 1·44 for a methyl group, which is not in agreement with 0·63-0·79 obtained from solvolytic rate data.
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    Photochemistry of matrix-isolated norbornadiene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 383-388 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Norbornadiene, isolated in argon, xenon and nitrogen matrices at 20 K, was irradiated with UV light. Characterized by UV-VIS-IR absorption spectroscopy the photoproduct, representing a single species, was assigned to quadricyclane. This result is compared with the literature data on photochemistry of norbornadiene in the gas and liquid phase. The role of the rigid matrix environment on selectivity of the photochemical reaction is discussed.
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Binding of pyridoxal-5′-phosphate and pyridoxamine-5′-phosphate: Electrochemical characterization (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 448-454 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The interaction between pyridoxal-5′-phosphate (PLP) and pyridoxamine-5′-phosphate (PMP) was studied by d.c. and differential pulse polarography. Two reduction waves (or two peaks) were observed. The first wave corresponds to the reduction of the adduct and the second to the reduction of free PLP. The behaviour was similar in analogous Schiff bases. The effects of pH, PMP concentration and the capillary characteristics were studied. The apparent formation constant as a function of the pH was calculated. Thermodynamic parameters were estimated at pH 7 and 0 · 1 M ionic strength. The polarographic and kinetic results show that the overall electrode process appears to be irreversible in a basic medium.
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    Dipole moments and electron distribution of acyl chlorides and acyl bromides (1989)
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    Journal of Physical Organic Chemistry 2 (1989), S. 476-483 
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    Keywords: Organic Chemistry ; Physical Chemistry
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    Notes: Dipole moments of para-substituted benzoyl chlorides and bromides, partly measured in benzene and partly recalculated from elderly literature, were analysed in terms of bond moments and additional contributions expressing the conjugation. Although the gross moments are similar, their decomposition yields different pictures for acyl chlorides and bromides. Only in the latter can significant electron transfer from the halogen be observed. On the other hand, conjugation with the benzene nucleus is strong in both aromatic acyl chlorides and bromides, but stronger in chlorides. There is agreement with the evidence from some other physical quantities but not from all.
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    Aromatic substitution by free benzyl cations from the nuclear decay of multi-tritiated toluene. Competitive benzylation of benzene and toluene in the gas phase and in solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 467-475 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Benzyl cations, free of counter ions, have been generated from the nuclear decay of tritium atoms contained exclusively in the side-chain of multi-labelled toluene and allowed to react in competition experiments with benzene and toluene. The aromatic substitution was studied in both the gaseous and liquid phase, employing pure aromatics or aromatics dissolved in n-hexane, carbon tetrachloride and nitromethane as the reaction medium. In the gaseous systems, at 20 Torr total pressure, High meta substitution of toluene indicates extensive isomerization of the excited intermediates, while the increase of the kT/kB value in the Presence of NH3 suggests that selective transalkylation competes with proton transfer to ammonia from the benzyl cation adducts with benzene, but not with toluene. High positional and low substrate selectivities were measured in solution, the decrease in kT/kB (from 2·8 to 1·7) in the different solvents being accompanied by an increase in the o/2p ratio. Competition experiments between benzene and methanol indicate that the reaction is not diffusion controlled. The influence of the reaction medium on the substrate selectivity is explained by postulating the formation of a cation-solvent adduct, where the solvent molecule undergoes displacement by the substrate. Positional selectivity would be controlled in a subsequent step.
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    Micellar catalysis of organic reactions. 24.For Part 23, see T. J. Broxton, J. R. Christie and R. P.-T. Chung, J. Org. Chem. 53, 3081 (1988). Comparison of SNAr reactions in hydroxy-functionalized micelles and in the presence of cyclodextrins (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 519-530 
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    Keywords: Organic Chemistry ; Physical Chemistry
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    Notes: The basic hydrolysis of 2,4-dinitrochlorobenzene (DNCB) and 2,4-dinitrofluorobenzene (DNFB) was studied in the presence of β-cyclodextrin (CDOH) and in the presence of hydroxy-functionalized micelles containing either a primary hydroxy group [hexadecyl-2-hydroxyethyldimethylammonium bromide (CHEDAB)] or a secondary hydroxy group [headecyl-2-hydroxypropyldimethylammonium bromide (CHPDAB) and 2-hydroxyhexadecyltrimethylammonium bromide (2-OHCTAB)].In all systems a biphasic reaction was observed. The first phase consisted of a competition between the additive (either micelle or cyclodextrin) and hydroxide ion for the aromatic substrate, and the second phase consisted of the hydrolysis of the trapped aryl micellar or cyclodextryl ether.The percentage of trapping of the aromatic substrate by the cyclodextrin was similar to that found for reactions in the hydroxy-functionalized micelles (CHPDAB and 2-OHCTAB) which contained secondary hydroxy groups. The relative rates of reaction for DNFB and for DNCB, i.e. F/Cl rate ratios, in the presence of CDOH were similar to those obtained in the presence of 2-OHCTAB but less than that obtained in the presence of CHEDAB. These results support the assumption that in CDOH the secondary hydroxy groups of C-2 or C-3 are involved in covalent bond formation with the aromatic substrate rather than the primary hydroxy group of C-6. All the reactions studied proceed much more slowly in the presence of CDOH than in the presence of the hydroxy-functionalized micelles. This may reflect a catalytic effect of the positively charged surface present in the micelles but not in the cyclodextrin.
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    Hydrogen-bonding 8.Part 7; M. H. Abraham, P. L. Grellier, D. V. Prior, P. P. Duce, J. J. Morris and P. J. Taylor. J. Chem Soc., Perkin Trans. 2, (in press). Possible equivalence of solute and solvent scales of hydrogen-bond basicity of non-associated compounds (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 540-552 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Using the solvatochromic indicator method, a scale of solvent hydrogen-bond basicity, β1 (General), has been set up using a series of double regression equations, \documentclass{article}\pagestyle{empty}\begin{document}$$ \nu = \nu _0 + s\pi _1^* + b\beta _1 $$\end{document} for 11 aniline-type indicators. A similar solvent scale, β1 (Special), has been constructed by the homomorphic comparison method using only results by Laurence et al. on the indicators 4-nitroaniline and 4-nitro-N,N-dimethylaniline. Results are available from our previous work on a general solute scale, β2H, and we have also obtained a special solute scale, β2 (pKHB) from available log K values for hydrogen-bond complexation of bases with 4-fluorophenol in CCl4. However, the two solute β2 scales are virtually identical.It is shown that there is a general connection between β1(General) and β2H, with r = 0·9775 and s.d. = 0·05 for 32 compounds, and between β1(Special) and β2H, with r = 0·9776 and s.d. = 0·06 for the same 32 compounds. The latter correlation over 60 compounds yields r = 0·9684 and s.d. = 0·07. However, there are so many compounds in these regressions for which the differences in the solvent and solute β values are larger than the total expected error of 0·07 units that the use of β1 to predict β2 or vice versa is a very hazardous procedure. About 70 new β1 values obtained by the double regression method are also reported.
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    Molecular mechanics (MM2) calculations on siloxanesThis paper is taken from Ref. 1. (1989)
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    Journal of Physical Organic Chemistry 2 (1989), S. 573-579 
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    Keywords: Organic Chemistry ; Physical Chemistry
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    Notes: The MM2 force field has been extended so that calculations may be carried out on siloxanes. The parameters chosen give a good fit to available experimental data.
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    Energy-minimum structure of the hydrocarbon portion of [45] (1,2,3,4,5)ferrocenophane (1989)
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    Journal of Physical Organic Chemistry 2 (1989), S. 602-610 
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    Notes: In order to assist in the interpretation of the D5h molecular structure of [45] (1,2,3,4,5)ferrocenophane (1) obtained from x-ray crystallographic analysis, a hypothetical hydrocarbon C30H40 (2) was derived from 1 by removing the iron atom and subjected to geometry optimization by molecular mechanics. A stable D5 conformer was found for 2, which has a g+ g- g+ helical bridge conformation and a ring-ring distance almost identical with that in 1 and ferrocene itself. Optimization of a perhydrogenated hydrocarbon model gave a highly strained C1 structure.
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    The double photodissociation of a geminal dichloride: Evidence for the stepwise formation of a diaryl carbene (1989)
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    Journal of Physical Organic Chemistry 2 (1989), S. 623-630 
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    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photolysis of dichlorodiphenylmethane in glassy 2-methyltetrahydrofuran at 77 K results in the formation of diphenylcarbene and the diphenylchloromethyl radical, which were detected by their fluorescence emission and excitation spectra. The relative yields of the carbene and biradical are shown to vary dramatically as a function of photolysis time. The photolability of the diphenylchloromethyl radical is also demonstrated. These results were interpreted in terms of a two-step mechanism, in which the diphenylchloromethyl radical is an intermediate in the formation of diphenylcarbene.
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    URL: http://dx.doi.org/10.1002/poc.610020805
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    Self-catalysis and molecular complexes in aromatic nucleophilic substitution reactions: Reaction between 1,3,5-trinitrobenzene and 1,8-diazabicyclo [5.4.0] undec-7-ene in toluene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 653-659 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of a σ-like complex by reaction between 1,3,5-trinitrobenzene and 1,8-diazabicyclo [5.4.0]-undec-7-ene was investigated in toluene at various temperatures. The kinetic data showed autocatalytic behaviour. Inspection of the reaction mixtures at zero reaction time indicated the presence of an equilibrium preceding the attack of the nucleophile, affording a molecular complex (substrate-nucleophile) which is responsible for the observed kinetic features. The present and the previous data led to the conclusion that the catalytic behaviours usually observed in SNAr reactions (in apolar solvents with amines as nucleophiles) are better explained by the presence of substrate-catalyst interactions than by catalysis on departure of the proton and leaving group from the zwitterionic intermediate.
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    URL: http://dx.doi.org/10.1002/poc.610020808
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    Switching of reaction pathways due to methylene chain length effects (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 187-204 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reaction products of bifunctional chain molecules with structure X—(CH2)n—Y may critically depend on the chain length n. When the chain length is short (n ≤ 5), reaction products particular to an intramolecular reaction can be dominant, while a process corresponding to an intermolecular reaction between X—CH3 and H3C—Y may take place for higher homologues having large n (≥10). The reaction switching dependent on n is explained in terms of the encounter probability for both end groups (X and Y) with conformations pertinent to product formation. The reaction switching of this sort is discussed on the basis of a reactivity profile recorded as a function of the chain length. Similar reactivity profiles have been observed for thermal Friedel-Crafts cyclization and photo-Smiles rearrangement/photoredox reaction. It is anticipated that the magic methylene chain length of 7 may give rise to an appreciable decrease in reaction yields (e.g. ‘difficulty in medium-sized ring closure’) or an anomalous switching of reaction pathways due to chain length effects.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020302
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    Long range electrical field effects in solvolysis and 13C-NMR shielding of androstanes with halogen, hydroxy and oxo substituents (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 214-224 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solvolysis of 21 different 3- or 17-androstanyl tosylates or chlorides with halogen, hydroxy or oxo substituents in 17- or 3-position shows rate constant variations in hexafluoro isopropanol of up to 6·3 with regular differences for epimeric substituents. Similar variations ae seen over a distance of ∼10 Å in 13C-NMR shifts at C-17-ones of androstan-17-ones with varied halogen substituents in C-3, whereas the shielding observed at other distant carbon atoms excludes significant through bond effects. It is shown how, on the basis of suitable Coulomb-type equations and of force field minimized geometries, both the stability variation of carbocationic transition states and the carbonyl group polarization are predictable by linear electric field effects, using the same parametrization.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020304
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    Alkylating properties of phosphate esters. 3. Reactivity of dialkyl 2-(dimethylamino) ethyl phosphates (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 263-270 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactivity of dialkyl 2-(dimethylamino)ethyl phosphates, (RO)2P(O)OCH2CH2NMe2 (R = Me, PhCH2) was studied in aqueous solutions. Depending on the initial substrate's concentration, reaction can involve the unimolecular fragmentation to N,N-dimethylaziridinium dialkylphosphate, or the bimolecular isomerization to the zwitterionic derivative. The latter reaction proceeds via two consecutive SN2 steps and involves the formation of two ionic intermediates which were synthesized independently and allowed to react to give the zwitterionic product. Rate constants for the isomerization of the dimethyl ester (R = Me), as well as rate constant for the reaction between the corresponding intermediates have been determined, and the reactivity of the dimethyl ester has been compared with that of the dibenzyl derivative.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020309
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    Influence of aromatic substituents on the configuration and conformation of calix[4]areneoctols (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 531-539 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Acid-catalysed condensation of resorcinol with aromatic aldehydes results in 2,8,14,20-tetrasubstitued calix[4] areneoctols. Sixteen compounds of this type containing different aromatic substituents were synthesized. The ring closure step, under the conditions of the reaction, is a reversible process. Four configurations are possible for every constitution, viz. cccc, cctt, ccct and ctct, but only cccc and cctt were formed in detectable amounts. In seven cases the thermodynamically more stable cccc isomers (1a-5a, 7a, 8a) and also the kinetically controlled cctt isomers (1b-5b, 7b, 8b) could be isolated. The configurations of the compounds were assigned by temperature-dependent 1H NMR analysis. The conformational motions of the macrocyclic ring permit only the cccc isomers to show coalescence for the signals of the aromatic Hb protons. The coalescence temperature was determined for isomers 1a (ΔG384≠ = 83·5 kJmol-1) and 3a (ΔG369≠ = 83·7 kJ mol-1). For steric reasons the ‘chair-chair’ conformers B and the ‘quasi-boat-chair’ conformers F are favoured. 1H and 13C NMR shifts show that compounds 1a-5a and 1b-5b have a quasi-axial arrangement of the aromatic substituents, whereas 6-9 have a quasi-equatorial arrangement of the substituents.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020705
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    Solute-solvent interactions in chemical and biological systems. IV. Correlations of ΔG, ΔH and TΔS of transfer of aliphatic and aromatic solutes from 2,2,4-trimethylpentane to aqueous solution (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 559-564 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ΔG, ΔH and TΔS of transfer of 25 aliphatic and aromatic solutes from 2,2,4-trimethylpentane to aqueous buffer (pH 7) at 298 K have been examined in terms of intrinsic volumes and the solvatochromic parameters π*, δ, β and α of the pure solutes Correlations of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ XYZ = XYZ_0 + {{mV_{\rm I} } \mathord{\left/ {\vphantom {{mV_{\rm I} } {100}}} \right. \kern-\nulldelimiterspace} {100}} + s\pi ^* + d\delta + d\beta + a\alpha $$\end{document} indicate that the thermodynamic quantities of transfer are unequally affected by solute properties; most notably, for aromatic solutes the cavity term mVI/100 is a principal (unfavorable) factor affecting TΔS, but has little effect on ΔH. Transfer to water is favored by increasing solute π* (dipolarity-polarizability), β (H-bond basicity) and α (H-bond acidity), because water has greater dipolarity, H-bond acidity and H-bond basicity than trimethylpentane. Hydrogen bonding contributes exothermically to ΔH, but unfavorably to TΔS, as would be expected from a loss of transitional entropy. Correlations of ΔG, ΔH and TΔS with solute VI/100, β, α, μ2 and polarizability function [(n2 - 1)/(n2 + 2)] give closely comparable results.
    Additional Material: 2 Tab.
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020801
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    Cation radical pericyclic reactions: CyclopropanationDedicated to Michael J. S. Dewar in the year of his seventieth birthday. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 585-601 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Triarylaminium salts smoothly catalyze the cyclopropanation of dienes, styrenes and tetrasubstituted alkenes by ethyl diazoacetate. The reactions are regioselective and, in the case of additions to conjugated dienes, cyclopropane-periselective. A cation radical chain mechanism involving carbene transfer from ethyl diazoacetate to a substrate cation radical is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020802
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    Calorimetric study of the effect of N-methylation in azoles: Loss of an active centre of solvation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 646-652 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using a series of equations connecting experimental and theoretical values, it is possible to discuss the origin of the N-methylation effect in azoles dissolved in water and dimethyl sulphoxide. The existence in the azoles studied of a linear relationship between the gas → solution transfer enthalpies and the charge on the pyrrole hydrogen atom demonstrated the fundamental importance of the loss of an active centre for solvation. For the imidazole-N-methylimidazole pair, the complete thermochemical cycle has been determined, allowing the apparent lack of an effect of N-methylation on the basicity in solution to be discussed.
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    URL: http://dx.doi.org/10.1002/poc.610020807
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    Oxidation of substituted ethanols by sodium N-bromobenzenesulphonamide: A kinetic study (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 660-671 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the oxidation of seven substituted ethanols by sodium N-bromobenzenesulphonamide or bromamine-B (BAB) in the presence of HCl was studied at 45 °C. The rate shows a first-order dependence on [BAB]0 and is fractional in [alcohol]0, [H+] and [Cl-]. Ionic strength variations, addition of benzenesulphonamide reaction product and variation of dielectric constant of the medium have no effect on the rate. The solvent isotope effect kH2O′/kD2O′ ≈ 0·97. The rates do not correlate satisfactorily with Taft's substituent constants. Activation parameters ΔH≠, ΔS≠, ΔG≠ and log A were calculated by studying the reaction at different temperatures (308-323 K). It was found that ΔH≠ and ΔS≠ are linearly related and an isokinetic relationship is observed with isokinetic temperature β = 393 K, indicating enthalpy as a controlling factor.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020809
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    Specific recognition of cruciform DNA by nuclear protein HMG1 (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-02-24
    Description: Cruciform DNA, a non-double helix form of DNA, can be generated as an intermediate in genetic recombination as well as from palindromic sequences under the effect of supercoiling. Eukaryotic cells are equipped with a DNA-binding protein that selectively recognizes cruciform DNA. Biochemical and immunological data showed that this protein is HMG1, an evolutionarily conserved, essential, and abundant component of the nucleus. The interaction with a ubiquitous protein points to a critical role for cruciform DNA conformations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bianchi, M E -- Beltrame, M -- Paonessa, G -- New York, N.Y. -- Science. 1989 Feb 24;243(4894 Pt 1):1056-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Molecular Biology Laboratory, Heidleberg, Federal Republic of Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2922595" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cloning, Molecular ; DNA/genetics/*metabolism ; Electrophoresis, Polyacrylamide Gel ; High Mobility Group Proteins/genetics/isolation & purification/*metabolism ; Immunoassay ; Immunoblotting ; Liver/analysis ; Molecular Sequence Data ; Molecular Weight ; *Nucleic Acid Conformation ; Peptide Fragments/genetics/isolation & purification ; Protein Biosynthesis ; Rats ; Transcription, Genetic
    Print ISSN: 0036-8075
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    Recognition of thymine adenine.base pairs by guanine in a pyrimidine triple helix motif (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-09-01
    Description: Oligonucleotide recognition offers a powerful chemical approach for the sequence-specific binding of double-helical DNA. In the pyrimidine-Hoogsteen model, a binding size of greater than 15 homopurine base pairs affords greater than 30 discrete sequence-specific hydrogen bonds to duplex DNA. Because pyrimidine oligonucleotides limit triple helix formation to homopurine tracts, it is desirable to determine whether oligonucleotides can be used to bind all four base pairs of DNA. A general solution would allow targeting of oligonucleotides (or their analogs) to any given sequence in the human genome. A study of 20 base triplets reveals that the triple helix can be extended from homopurine to mixed sequences. Guanine contained within a pyrimidine oligonucleotide specifically recognizes thymine.adenine base pairs in duplex DNA. Such specificity allows binding at mixed sites in DNA from simian virus 40 and human immunodeficiency virus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Griffin, L C -- Dervan, P B -- GM-35724/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 1;245(4921):967-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2549639" target="_blank"〉PubMed〈/a〉
    Keywords: *Adenine ; Base Sequence ; DNA/*genetics ; DNA, Viral/genetics ; *Guanine ; HIV/genetics ; Hydrogen Bonding ; Models, Structural ; Molecular Sequence Data ; *Nucleic Acid Conformation ; Oligodeoxyribonucleotides ; Simian virus 40/genetics ; *Thymine
    Print ISSN: 0036-8075
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    Kappa B-specific DNA binding proteins: role in the regulation of human interleukin-2 gene expression (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-04-28
    Description: Transcriptional activation of the human interleukin-2 (IL-2) gene, like induction of the IL-2 receptor alpha (IL-2R alpha) gene and the type 1 human immunodeficiency virus (HIV-1), is shown to be modulated by a kappa B-like enhancer element. Mutation of a kappa B core sequence identified in the IL-2 promoter (-206 to -195) partially inhibits both mitogen- and HTLV-I Tax-mediated activation of this transcription unit and blocks the specific binding of two inducible cellular factors. These kappa B-specific proteins (80 to 90 and 50 to 55 kilodaltons) similarly interact with the functional kappa B enhancer present in the IL-2R alpha promoter. These data suggest that these kappa B-specific proteins have a role in the coordinate regulation of this growth factor-growth factor receptor gene system that controls T cell proliferation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hoyos, B -- Ballard, D W -- Bohnlein, E -- Siekevitz, M -- Greene, W C -- A127053-01/PHS HHS/ -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):457-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Mount Sinai Medical Center, Department of Microbiology, New York, NY 10029.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2497518" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cell Line ; Cloning, Molecular ; DNA/metabolism ; DNA-Binding Proteins/*metabolism ; *Enhancer Elements, Genetic ; *Gene Expression Regulation ; Genes, Viral ; HIV-1/genetics ; HTLV-I Antigens/pharmacology ; Humans ; Immunoglobulin kappa-Chains/*genetics ; Interleukin-2/*genetics ; Molecular Weight ; Mutation ; Phytohemagglutinins/pharmacology ; Plasmids ; Promoter Regions, Genetic ; RNA, Messenger/biosynthesis ; T-Lymphocytes/metabolism ; Tetradecanoylphorbol Acetate/pharmacology ; Trans-Activators ; Transcription Factors/pharmacology ; Transcription, Genetic ; Transfection
    Print ISSN: 0036-8075
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    Generation of a large combinatorial library of the immunoglobulin repertoire in phage lambda (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-12-08
    Description: A novel bacteriophage lambda vector system was used to express in Escherichia coli a combinatorial library of Fab fragments of the mouse antibody repertoire. The system allows rapid and easy identification of monoclonal Fab fragments in a form suitable for genetic manipulation. It was possible to generate, in 2 weeks, large numbers of monoclonal Fab fragments against a transition state analog hapten. The methods described may supersede present-day hybridoma technology and facilitate the production of catalytic and other antibodies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huse, W D -- Sastry, L -- Iverson, S A -- Kang, A S -- Alting-Mees, M -- Burton, D R -- Benkovic, S J -- Lerner, R A -- New York, N.Y. -- Science. 1989 Dec 8;246(4935):1275-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2531466" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antibodies, Monoclonal/*biosynthesis/genetics ; Antibody Specificity ; Antigen-Antibody Reactions ; Bacteriophage lambda/*genetics ; Base Sequence ; Cloning, Molecular/methods ; Escherichia coli/genetics ; Gene Amplification ; Gene Library ; *Genetic Vectors ; Hemocyanin/analogs & derivatives/immunology ; Immunoglobulin Fab Fragments/biosynthesis ; Immunoglobulin Fragments/*biosynthesis/genetics ; Mice ; Molecular Sequence Data ; Organophosphorus Compounds/immunology ; Recombinant Proteins/biosynthesis/genetics
    Print ISSN: 0036-8075
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    Golf: an olfactory neuron specific-G protein involved in odorant signal transduction (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-05-19
    Description: Biochemical and electrophysiological studies suggest that odorants induce responses in olfactory sensory neurons via an adenylate cyclase cascade mediated by a G protein. An olfactory-specific guanosine triphosphate (GTP)-binding protein alpha subunit has now been characterized and evidence is presented suggesting that this G protein, termed Golf, mediates olfaction. Messenger RNA that encodes Golf alpha is expressed in olfactory neuroephithelium but not in six other tissues tested. Moreover, within the olfactory epithelium, Golf alpha appears to be expressed only by the sensory neurons. Specific antisera were used to localize Golf alpha protein to the sensory apparatus of the receptor neurons. Golf alpha shares extensive amino acid identity (88 percent) with the stimulatory G protein, Gs alpha. The expression of Golf alpha in S49 cyc- kin- cells, a line deficient in endogenous stimulatory G proteins, demonstrates its capacity to stimulate adenylate cyclase in a heterologous system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jones, D T -- Reed, R R -- New York, N.Y. -- Science. 1989 May 19;244(4906):790-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biology and Genetic Johns Hopkins School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2499043" target="_blank"〉PubMed〈/a〉
    Keywords: Adenylyl Cyclases/metabolism ; Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; GTP-Binding Proteins/analysis/genetics/*physiology ; Gene Expression Regulation ; Immunoblotting ; Immunohistochemistry ; Molecular Sequence Data ; Neurons, Afferent/analysis/*physiology ; *Odors ; Olfactory Bulb/physiology ; Olfactory Mucosa/analysis/*innervation ; RNA, Messenger/analysis/genetics ; Rats ; Sequence Homology, Nucleic Acid ; *Signal Transduction ; Tissue Distribution ; Transfection
    Print ISSN: 0036-8075
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    Vascular permeability factor, an endothelial cell mitogen related to PDGF (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-12-08
    Description: Vascular permeability factor (VPF) is a 40-kilodalton disulfide-linked dimeric glycoprotein that is active in increasing blood vessel permeability, endothelial cell growth, and angiogenesis. These properties suggest that the expression of VPF by tumor cells could contribute to the increased neovascularization and vessel permeability that are associated with tumor vasculature. The cDNA sequence of VPF from human U937 cells was shown to code for a 189-amino acid polypeptide that is similar in structure to the B chain of platelet-derived growth factor (PDGF-B) and other PDGF-B-related proteins. The overall identity with PDGF-B is 18%. However, all eight of the cysteines in PDGF-B were found to be conserved in human VPF, an indication that the folding of the two proteins is probably similar. Clusters of basic amino acids in the COOH-terminal halves of human VPF and PDGF-B are also prevalent. Thus, VPF appears to be related to the PDGF/v-sis family of proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keck, P J -- Hauser, S D -- Krivi, G -- Sanzo, K -- Warren, T -- Feder, J -- Connolly, D T -- New York, N.Y. -- Science. 1989 Dec 8;246(4935):1309-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Culture and Biochemistry, Monsanto Company, St. Louis, MO 63167.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2479987" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Capillary Permeability/physiology ; Cell Division/physiology ; Cloning, Molecular ; Endothelium, Vascular/*cytology ; *Growth Substances ; Guinea Pigs ; Humans ; Lymphokines/*physiology ; Molecular Sequence Data ; Neovascularization, Pathologic/physiopathology ; Oncogene Proteins v-sis ; Platelet-Derived Growth Factor/physiology ; Retroviridae Proteins, Oncogenic/physiology ; Sequence Homology, Nucleic Acid ; Transforming Growth Factors ; Vascular Endothelial Growth Factor A ; Vascular Endothelial Growth Factors
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    cis-trans models for post-transcriptional gene regulation (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-11-17
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Klausner, R D -- Harford, J B -- New York, N.Y. -- Science. 1989 Nov 17;246(4932):870-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2683086" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; *Gene Expression Regulation ; *Models, Genetic ; Molecular Sequence Data ; Nucleic Acid Conformation ; *Protein Biosynthesis ; RNA, Messenger/genetics ; Transcription, Genetic
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 80
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    Translational blockade imposed by cytokine-derived UA-rich sequences (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-08-25
    Description: The messenger RNAs specifying certain proteins involved in the inflammatory response and certain oncoproteins contain a conserved UA-rich sequence in the 3' untranslated region. This sequence, which is composed of several interspersed repeats of the octanucleotide UUAUUUAU, has been shown to destabilize mRNA in some eukaryotes. However, this effect is not seen when mRNAs are transferred to Xenopus oocytes, which made it possible to separate stability from translational regulation. For interferon, granulocyte-macrophage colony-stimulating factor, and c-fos RNAs, the UA-rich sequence was observed to preclude mRNA translation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kruys, V -- Marinx, O -- Shaw, G -- Deschamps, J -- Huez, G -- New York, N.Y. -- Science. 1989 Aug 25;245(4920):852-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departement de Biologie Moleculaire, Universite Libre de Bruxelles, Belgium.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2672333" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Colony-Stimulating Factors/*genetics ; Granulocyte-Macrophage Colony-Stimulating Factor ; Growth Substances/*genetics ; Interferon Type I/*genetics ; Molecular Sequence Data ; *Protein Biosynthesis ; *Proto-Oncogenes ; RNA, Messenger/metabolism
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  • 81
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    Sequence-specific isotope effects on the cleavage of DNA by bleomycin (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-09-22
    Description: Bleomycin is a metal- and oxygen-dependent DNA cleaver. The chemistry of DNA damage has been proposed to involve rate-limiting abstraction of the 4'-hydrogen. A DNA fragment has been prepared that contains [4'-2H]thymidine residues of high isotopic content. Primary kinetic isotope effects have been directly observed at individual thymidine residues with DNA sequencing technology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kozarich, J W -- Worth, L Jr -- Frank, B L -- Christner, D F -- Vanderwall, D E -- Stubbe, J -- GM 34454/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 22;245(4924):1396-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2476851" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; *Bleomycin ; *DNA Damage ; Deuterium ; Iron ; Oxygen ; Structure-Activity Relationship ; Thymidine
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 82
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    Adenylyl cyclase amino acid sequence: possible channel- or transporter-like structure (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-06-30
    Description: Complementary DNA's that encode an adenylyl cyclase were isolated from a bovine brain library. Most of the deduced amino acid sequence of 1134 residues is divisible into two alternating sets of hydrophobic and hydrophilic domains. Each of the two large hydrophobic domains appears to contain six transmembrane spans. Each of the two large hydrophilic domains contains a sequence that is homologous to a single cytoplasmic domain of several guanylyl cyclases; these sequences may represent nucleotide binding sites. An unexpected topographical resemblance between adenylyl cyclase and various plasma membrane channels and transporters was observed. This structural complexity suggests possible, unappreciated functions for this important enzyme.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Krupinski, J -- Coussen, F -- Bakalyar, H A -- Tang, W J -- Feinstein, P G -- Orth, K -- Slaughter, C -- Reed, R R -- Gilman, A G -- CA16519/CA/NCI NIH HHS/ -- GM12230/GM/NIGMS NIH HHS/ -- GM34497/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1989 Jun 30;244(4912):1558-64.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2472670" target="_blank"〉PubMed〈/a〉
    Keywords: *Adenylyl Cyclases/genetics/isolation & purification ; Amino Acid Sequence ; Animals ; Base Sequence ; Brain/enzymology ; *Carrier Proteins ; Cattle ; Cell Line ; Cloning, Molecular ; DNA/genetics ; Electrophoresis, Polyacrylamide Gel ; *Ion Channels ; Membrane Proteins ; Molecular Sequence Data ; Nucleic Acid Hybridization ; Protein Conformation ; Transfection
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  • 83
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    DNA mismatch correction in a defined system (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-07-14
    Description: DNA mismatch correction is a strand-specific process involving recognition of noncomplementary Watson-Crick nucleotide pairs and participation of widely separated DNA sites. The Escherichia coli methyl-directed reaction has been reconstituted in a purified system consisting of MutH, MutL, and MutS proteins, DNA helicase II, single-strand DNA binding protein, DNA polymerase III holoenzyme, exonuclease I, DNA ligase, along with ATP (adenosine triphosphate), and the four deoxynucleoside triphosphates. This set of proteins can process seven of the eight base-base mismatches in a strand-specific reaction that is directed by the state of methylation of a single d(GATC) sequence located 1 kilobase from the mispair.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lahue, R S -- Au, K G -- Modrich, P -- F32 GM12684/GM/NIGMS NIH HHS/ -- GM23719/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Jul 14;245(4914):160-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Duke University Medical Center, Durham, NC 27710.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2665076" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; *DNA Repair ; DNA, Bacterial/biosynthesis/*genetics ; Escherichia coli/*genetics ; Methylation ; Mutation
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 84
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    Reverse transcriptase in a clinical strain of Escherichia coli: production of branched RNA-linked msDNA (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-02-24
    Description: Branched RNA-linked multicopy single-stranded DNA (msDNA) originally detected in myxobacteria has now been found in a clinical isolate of Escherichia coli. Although lacking homology in the primary structure, the E. coli msDNA is similar in secondary structure to the myxobacterial msDNA's, including the 2',5'-phosphodiester linkage between RNA and DNA. A chromosomal DNA fragment responsible for the production of msDNA was cloned in an E. coli K12 strain; its DNA sequence revealed an open reading frame (ORF) of 586 amino acid residues. The ORF shows sequence similarity with retroviral reverse transcriptases and ribonuclease H. Disruption of the ORF blocked msDNA production, indicating that this gene is essential for msDNA synthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lampson, B C -- Sun, J -- Hsu, M Y -- Vallejo-Ramirez, J -- Inouye, S -- Inouye, M -- F32 GM11970-01A1/GM/NIGMS NIH HHS/ -- GM26843/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Feb 24;243(4894 Pt 1):1033-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2466332" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Cloning, Molecular ; DNA Probes ; DNA Restriction Enzymes ; DNA, Bacterial/genetics ; DNA, Single-Stranded/analysis/biosynthesis/*genetics ; Endoribonucleases/genetics ; Escherichia coli/enzymology/*genetics ; Genes, Bacterial ; HIV/enzymology/genetics ; Human T-lymphotropic virus 1/enzymology/genetics ; Molecular Sequence Data ; Myxococcales/genetics ; Nucleic Acid Hybridization ; RNA, Bacterial/analysis/biosynthesis/*genetics ; RNA-Directed DNA Polymerase/*genetics ; Retroviridae/*enzymology/genetics ; Ribonuclease H ; Sequence Homology, Nucleic Acid ; Transformation, Bacterial
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  • 85
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    Membrane anchoring of a human IgG Fc receptor (CD16) determined by a single amino acid (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-12-22
    Description: CD16 is a low-affinity immunoglobulin G (IgG) Fc receptor that is expressed on natural killer (NK) cells, granulocytes, activated macrophages, and some T lymphocytes. Two similar genes, CD16-I and CD16-II, encode membrane glycoproteins that are anchored by phosphatidylinositol (PI)-glycan and transmembrane polypeptides, respectively. The primary structural requirements for PI-linkage were examined by constructing a series of hybrid cDNA molecules. Although both cDNA's have an identical COOH-terminal hydrophobic segment, CD16-I has Ser203 whereas CD16-II has Phe203. Conversion of Phe to Ser in CD16-II permits expression of a PI-glycan-anchored glycoprotein, whereas conversion of Ser to Phe in CD16-I prevents PI-glycan linkage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lanier, L L -- Cwirla, S -- Yu, G -- Testi, R -- Phillips, J H -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1611-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Becton Dickinson Monoclonal Center, Inc., Mountain View, CA 94043.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2531919" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD/*genetics ; Antigens, Differentiation/*genetics/metabolism ; Base Sequence ; Cell Line ; Cell Membrane/immunology ; Codon/genetics ; *Genes, Immunoglobulin ; Granulocytes/immunology ; Humans ; Membrane Glycoproteins/*genetics ; Molecular Sequence Data ; *Phenylalanine ; Receptors, Fc/*genetics/metabolism ; Receptors, IgG ; *Serine ; Transfection
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  • 86
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    Defining the inside and outside of a catalytic RNA molecule (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-07-21
    Description: Ribozymes are RNA molecules that catalyze biochemical reactions. Fe(II)-EDTA, a solvent-based reagent which cleaves both double- and single-stranded RNA, was used to investigate the structure of the Tetrahymena ribozyme. Regions of cleavage alternate with regions of substantial protection along the entire RNA molecule. In particular, most of the catalytic core shows greatly reduced cleavage. These data constitute experimental evidence that an RNA enzyme, like a protein enzyme, has an interior and an exterior. Determination of positions where the phosphodiester backbone of the RNA is on the inside or on the outside of the molecule provides major constraints for modeling the three-dimensional structure of the Tetrahymena ribozyme. This approach should be generally informative for structured RNA molecules.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Latham, J A -- Cech, T R -- GM 11227-03/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Jul 21;245(4915):276-82.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2501870" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autoradiography ; Base Sequence ; Binding Sites ; Crystallography ; Edetic Acid ; Electrophoresis, Polyacrylamide Gel ; Ferrous Compounds ; Molecular Sequence Data ; Molecular Structure ; *Nucleic Acid Conformation ; *RNA Splicing ; RNA, Catalytic ; RNA, Fungal/analysis ; *RNA, Ribosomal/analysis/metabolism ; RNA, Transfer, Phe/analysis ; Tetrahymena/*genetics
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  • 87
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    Identification of the molecular defect in a family with spondyloepiphyseal dysplasia (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-05-26
    Description: Spondyloepiphyseal dysplasias (SED) are a heterogeneous group of inherited disorders characterized by disproportionate short stature and pleiotropic involvement of the skeletal and ocular systems. Evidence has suggested that SED may result from structural defects in type II collagen. To confirm the validity of this hypothesis, the structure of the "candidate" type II collagen gene (COL2A1) has been directly examined in a relatively large SED family. Coarse scanning of the gene by Southern blot hybridization identified an abnormal restriction pattern in one of the affected members of the kindred. Analysis of selected genomic fragments, amplified by the polymerase chain reaction, precisely localized the molecular defect and demonstrated that all affected family members carried the same heterozygous single-exon deletion. As a consequence of the mutation, nearly 90 percent of the assembled type II collagen homotrimers are expected to contain one or more procollagen subunits harboring an interstitial deletion of 36 amino acids in the triple helical domain.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, B -- Vissing, H -- Ramirez, F -- Rogers, D -- Rimoin, D -- AR-38648/AR/NIAMS NIH HHS/ -- HD-22657/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1989 May 26;244(4907):978-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, State University of New York Health Science Center, Brooklyn 11203.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2543071" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Child, Preschool ; Chromosome Deletion ; Collagen/*genetics ; DNA Restriction Enzymes ; DNA-Directed DNA Polymerase ; Exons ; Female ; Gene Amplification ; Humans ; Macromolecular Substances ; Male ; Molecular Sequence Data ; Mutation ; Nucleic Acid Hybridization ; Osteochondrodysplasias/*genetics ; Pedigree ; Procollagen/genetics
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  • 88
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    High rate of HTLV-II infection in seropositive i.v. drug abusers in New Orleans (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-04-28
    Description: Confirmed infection with HTLV-II (human T cell leukemia virus type II) has been described only in rare cases. The major limitation to serological diagnosis of HTLV-II has been the difficulty of distinguishing HTLV-II from HTLV-I (human T cell leukemia virus type I) infection, because of substantial cross-reactivity between the viruses. A sensitive modification of the polymerase chain reaction method was used to provide unambiguous molecular evidence that a significant proportion of intravenous drug abusers are infected with HTLV, and the majority of these individuals are infected with HTLV-II rather than HTLV-I. Of 23 individuals confirmed by polymerase chain reaction analysis to be infected with HTLV, 21 were identified to be infected with HTLV-II, and 2 were infected with HTLV-I. Molecular identification of an HTLV-II--infected population provides an opportunity to investigate the pathogenicity of HTLV-II in humans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, H -- Swanson, P -- Shorty, V S -- Zack, J A -- Rosenblatt, J D -- Chen, I S -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):471-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Diagnostics Division, Abbott Laboratories, North Chicago, IL 60064.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2655084" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; DNA, Viral/analysis ; DNA-Directed DNA Polymerase ; Genes, Viral ; HTLV-I Antibodies/analysis ; HTLV-I Infections/diagnosis/epidemiology/etiology ; HTLV-II Antibodies/*analysis ; HTLV-II Infections/diagnosis/*epidemiology/etiology ; Human T-lymphotropic virus 1/genetics/immunology ; Human T-lymphotropic virus 2/genetics/immunology ; Humans ; Immunoblotting ; Immunoenzyme Techniques ; Louisiana ; Molecular Sequence Data ; Sequence Homology, Nucleic Acid ; Substance-Related Disorders/*complications
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  • 89
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    Purification and complementary DNA cloning of a receptor for basic fibroblast growth factor (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-07-07
    Description: Basic fibroblast growth factor (bFGF) participates in many processes including early developmental events, angiogenesis, wound healing, and maintenance of neuronal cell viability. A 130-kilodalton protein was isolated on the basis of its ability to specifically bind to bFGF. A complementary DNA clone was isolated with an oligonucleotide probe corresponding to determined amino acid sequences of tryptic peptide fragments of the purified protein. The putative bFGF receptor encoded by this complementary DNA is a transmembrane protein that contains three extracellular immunoglobulin-like domains, an unusual acidic region, and an intracellular tyrosine kinase domain. These domains are arranged in a pattern that is different from that of any growth factor receptor described.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, P L -- Johnson, D E -- Cousens, L S -- Fried, V A -- Williams, L T -- CA 21765/CA/NCI NIH HHS/ -- R01 HL32898/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jul 7;245(4913):57-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Medicine, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2544996" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cells, Cultured ; Chick Embryo ; *Cloning, Molecular ; DNA/*genetics ; Fibroblast Growth Factors/*genetics ; Kinetics ; Mice ; Molecular Sequence Data ; Peptide Fragments/analysis ; Receptors, Cell Surface/*genetics/metabolism ; Receptors, Fibroblast Growth Factor ; Recombinant Proteins/metabolism
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  • 90
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    Vascular endothelial growth factor is a secreted angiogenic mitogen (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-12-08
    Description: Vascular endothelial growth factor (VEGF) was purified from media conditioned by bovine pituitary folliculostellate cells (FC). VEGF is a heparin-binding growth factor specific for vascular endothelial cells that is able to induce angiogenesis in vivo. Complementary DNA clones for bovine and human VEGF were isolated from cDNA libraries prepared from FC and HL60 leukemia cells, respectively. These cDNAs encode hydrophilic proteins with sequences related to those of the A and B chains of platelet-derived growth factor. DNA sequencing suggests the existence of several molecular species of VEGF. VEGFs are secreted proteins, in contrast to other endothelial cell mitogens such as acidic or basic fibroblast growth factors and platelet-derived endothelial cell growth factor. Human 293 cells transfected with an expression vector containing a bovine or human VEGF cDNA insert secrete an endothelial cell mitogen that behaves like native VEGF.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Leung, D W -- Cachianes, G -- Kuang, W J -- Goeddel, D V -- Ferrara, N -- New York, N.Y. -- Science. 1989 Dec 8;246(4935):1306-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Genetech, South San Francisco, CA 94080.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2479986" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Blotting, Northern ; Cattle ; Cell Division ; Cloning, Molecular ; Endothelium, Vascular/*cytology ; Gene Library ; Humans ; Lymphokines/genetics/*physiology/secretion ; Molecular Sequence Data ; Neovascularization, Pathologic/*physiopathology ; Sequence Homology, Nucleic Acid ; Vascular Endothelial Growth Factor A ; Vascular Endothelial Growth Factors
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  • 91
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    Selective amplification and cloning of four new members of the G protein-coupled receptor family (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-05-05
    Description: An approach based on the polymerase chain reaction has been devised to clone new members of the family of genes encoding guanosine triphosphate-binding protein (G protein)-coupled receptors. Degenerate primers corresponding to consensus sequences of the third and sixth transmembrane segments of available receptors were used to selectively amplify and clone members of this gene family from thyroid complementary DNA. Clones encoding three known receptors and four new putative receptors were obtained. Sequence comparisons established that the new genes belong to the G protein-coupled receptor family. Close structural similarity was observed between one of the putative receptors and the 5HT1a receptor. Two other molecules displayed common sequence characteristics, suggesting that they are members of a new subfamily of receptors with a very short nonglycosylated (extracellular) amino-terminal extension.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Libert, F -- Parmentier, M -- Lefort, A -- Dinsart, C -- Van Sande, J -- Maenhaut, C -- Simons, M J -- Dumont, J E -- Vassart, G -- New York, N.Y. -- Science. 1989 May 5;244(4904):569-72.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut de Recherche Interdisciplinaire, Faculte de Medecine, Universite Libre de Bruxelles, Campus Erasme, Belgium.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2541503" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; *Cloning, Molecular ; DNA/genetics ; DNA-Directed DNA Polymerase ; GTP-Binding Proteins/*metabolism ; *Gene Amplification ; Humans ; Molecular Sequence Data ; Receptors, Adrenergic, alpha/genetics ; Receptors, Adrenergic, beta/genetics ; Receptors, Muscarinic/genetics ; Receptors, Neurokinin-2 ; Receptors, Neurotransmitter/*genetics ; Receptors, Serotonin/genetics ; Sequence Homology, Nucleic Acid ; Thyroid Gland/analysis ; Transcription, Genetic
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  • 92
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    Polymerase chain reaction with single-sided specificity: analysis of T cell receptor delta chain (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-01-13
    Description: In the polymerase chain reaction (PCR), two specific oligonucleotide primers are used to amplify the sequences between them. However, this technique is not suitable for amplifying genes that encode molecules where the 5' portion of the sequences of interest is not known, such as the T cell receptor (TCR) or immunoglobulins. Because of this limitation, a novel technique, anchored polymerase chain reaction (A-PCR), was devised that requires sequence specificity only on the 3' end of the target fragment. It was used to analyze TCR delta chain mRNA's from human peripheral blood gamma delta T cells. Most of these cells had a V delta gene segment not previously described (V delta 3), and the delta chain junctional sequences formed a discrete subpopulation compared with those previously reported.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Loh, E Y -- Elliott, J F -- Cwirla, S -- Lanier, L L -- Davis, M M -- New York, N.Y. -- Science. 1989 Jan 13;243(4888):217-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departments of Medicine and Microbiology and Immunology, Stanford University School of Medicine, CA 94305-5402.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2463672" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Cell Line ; Gene Amplification ; *Genes ; Humans ; Macromolecular Substances ; Molecular Sequence Data ; Oligonucleotide Probes ; RNA, Messenger/genetics ; RNA-Directed DNA Polymerase ; Receptors, Antigen, T-Cell/*genetics ; T-Lymphocytes/immunology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 93
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    Recombinant 47-kilodalton cytosol factor restores NADPH oxidase in chronic granulomatous disease (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-07-28
    Description: A 47-kilodalton neutrophil cytosol factor (NCF-47k), required for activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase superoxide (O2-.) production, is absent in most patients with autosomal recessive chronic granulomatous disease (AR-CGD). NCF-47k cDNAs were cloned from an expression library. The largest clone predicted a 41.9-kD protein that contained an arginine and serine-rich COOH-terminal domain with potential protein kinase C phosphorylation sites. A 33-amino acid segment of NCF-47k shared 49% identity with ras p21 guanosine triphosphatase activating protein. Recombinant NCF-47k restored O2-. -producing activity to AR-CGD neutrophil cytosol in a cell-free assay. Production of active recombinant NCF-47k will enable functional regions of this molecule to be mapped.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lomax, K J -- Leto, T L -- Nunoi, H -- Gallin, J I -- Malech, H L -- New York, N.Y. -- Science. 1989 Jul 28;245(4916):409-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Bacterial Diseases Section, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2547247" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Blotting, Northern ; Cloning, Molecular ; DNA/*genetics ; Granulomatous Disease, Chronic/enzymology/*genetics ; Humans ; Immunoblotting ; Molecular Sequence Data ; NADH, NADPH Oxidoreductases/*metabolism ; NADPH Oxidase ; Neutrophils/*metabolism ; Phosphoproteins/*genetics/metabolism ; Phosphorylation ; Recombinant Proteins/genetics/metabolism ; Superoxides/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 94
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    Correct folding of circularly permuted variants of a beta alpha barrel enzyme in vivo (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-01-13
    Description: An important question in protein folding is whether the natural amino and carboxyl termini and the given order of secondary structure segments are critical to the stability and to the folding pathway of proteins. Here it is shown that two circularly permuted versions of the gene of a single-domain beta alpha barrel enzyme can be expressed in Escherichia coli. The variants are enzymically active and are practically indistinguishable from the original enzyme by several structural and spectroscopic criteria, despite the creation of new termini and the cleavage of a surface loop. This novel genetic approach should be useful for protein folding studies both in vitro and in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luger, K -- Hommel, U -- Herold, M -- Hofsteenge, J -- Kirschner, K -- New York, N.Y. -- Science. 1989 Jan 13;243(4888):206-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Abteilung Biophysikalische Chemie, Universitat Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2643160" target="_blank"〉PubMed〈/a〉
    Keywords: *Aldose-Ketose Isomerases ; Amino Acid Sequence ; Base Sequence ; Carbohydrate Epimerases/*genetics/metabolism ; Circular Dichroism ; *Cloning, Molecular ; Enzyme Stability ; Escherichia coli/*enzymology/genetics ; *Genes ; Genetic Variation ; Kinetics ; Molecular Sequence Data ; *Protein Conformation ; Spectrometry, Fluorescence ; Spectrophotometry, Ultraviolet
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 95
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    Cloning and sequencing of porcine LH-hCG receptor cDNA: variants lacking transmembrane domain (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-08-04
    Description: Complementary DNA clones, encoding the LH-hCG (luteinizing hormone-human choriogonadotropic hormone) receptor were isolated by screening a lambda gt11 library with monoclonal antibodies. The primary structure of the protein was deduced from the DNA sequence analysis; the protein contains 696 amino acids with a putative signal peptide of 27 amino acids. Hydropathy analysis suggests the existence of seven transmembrane domains that show homology with the corresponding regions of other G protein-coupled receptors. Three other types of clones corresponding to shorter proteins were observed, in which the putative transmembrane domain was absent. These probably arose through alternative splicing. RNA blot analysis showed similar patterns in testis and ovary with a major RNA of 4700 nucleotides and several minor species. The messenger RNA was expressed in COS-7 cells, yielding a protein that bound hCG with the same affinity as the testicular receptor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Loosfelt, H -- Misrahi, M -- Atger, M -- Salesse, R -- Vu Hai-Luu Thi, M T -- Jolivet, A -- Guiochon-Mantel, A -- Sar, S -- Jallal, B -- Garnier, J -- New York, N.Y. -- Science. 1989 Aug 4;245(4917):525-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut National de la Sante et de la Recherche Medicale Unite 135, Hopital de Bicetre, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2502844" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cell Membrane/*metabolism ; *Cloning, Molecular ; DNA/*genetics ; Female ; GTP-Binding Proteins/metabolism ; Male ; Molecular Sequence Data ; Mutation ; Nucleic Acid Hybridization ; Ovary/analysis ; Protein Sorting Signals/genetics ; RNA, Messenger/analysis/genetics ; Receptors, LH/*genetics/metabolism ; Sequence Homology, Nucleic Acid ; Swine ; Testis/analysis ; Tissue Distribution
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 96
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    Identification of an AUUUA-specific messenger RNA binding protein (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-11-03
    Description: An important control point in gene expression is at the level of messenger RNA (mRNA) stability. The mRNAs of certain regulatory cellular proteins such as oncogenes, cytokines, lymphokines, and transcriptional activators are extremely labile. These messages share a common AUUUA pentamer in their 3' untranslated region, which confers cytoplasmic instability. A cytosolic protein was identified that binds specifically to RNA molecules containing four reiterations of the AUUUA structural element. This protein consists of three subunits and binds rapidly to AUUUA-containing RNA. Such protein-RNA complexes are resistant to the actions of denaturing and reducing agents, demonstrating very stable binding. The time course, stability, and specificity of the protein-AUUUA interaction suggests the possibility that the formation of this complex may target susceptible mRNA for rapid cytoplasmic degradation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malter, J S -- CA01427-01/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1989 Nov 3;246(4930):664-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Tulane University School of Medicine, New Orleans, LA 70112.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814487" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding, Competitive ; Carrier Proteins/isolation & purification/*metabolism ; Cell Line ; Humans ; Kinetics ; Macromolecular Substances ; Molecular Weight ; *Nucleocytoplasmic Transport Proteins ; RNA, Messenger/*metabolism ; *RNA-Binding Proteins ; Ribonuclease, Pancreatic
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 97
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    Human KGF is FGF-related with properties of a paracrine effector of epithelial cell growth (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-08-18
    Description: Keratinocyte growth factor (KGF) is a human mitogen that is specific for epithelial cells. The complementary DNA sequence of KGF demonstrates that it is a member of the fibroblast growth factor family. The KGF transcript was present in stromal cells derived from epithelial tissues. By comparison with the expression of other epithelial cell mitogens, only KGF, among known human growth factors, has the properties of a stromal mediator of epithelial cell proliferation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finch, P W -- Rubin, J S -- Miki, T -- Ron, D -- Aaronson, S A -- New York, N.Y. -- Science. 1989 Aug 18;245(4919):752-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2475908" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cell Division ; Codon ; DNA/genetics/isolation & purification ; Epithelial Cells ; Epithelium/analysis/metabolism ; Fibroblast Growth Factor 10 ; Fibroblast Growth Factor 7 ; *Fibroblast Growth Factors/genetics ; Fibroblasts/metabolism ; Gene Expression Regulation ; Growth Substances/*genetics/physiology ; Humans ; Mesoderm/metabolism ; Mice ; Molecular Sequence Data ; Nucleic Acid Hybridization ; Oligonucleotide Probes ; RNA/analysis ; Sequence Homology, Nucleic Acid ; Skin/analysis ; Tissue Distribution ; Transcription, Genetic
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 98
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    Human diabetes associated with a mutation in the tyrosine kinase domain of the insulin receptor (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-07-07
    Description: Insulin receptor complementary DNA has been cloned from an insulin-resistant individual whose receptors have impaired tyrosine protein kinase activity. One of this individual's alleles has a mutation in which valine is substituted for Gly996, the third glycine in the conserved Gly-X-Gly-X-X-Gly motif in the putative binding site fo adenosine triphosphate. Expression of the mutant receptor by transfection into Chinese hamster ovary cells confirmed that the mutation impairs tyrosine kinase activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Odawara, M -- Kadowaki, T -- Yamamoto, R -- Shibasaki, Y -- Tobe, K -- Accili, D -- Bevins, C -- Mikami, Y -- Matsuura, N -- Akanuma, Y -- New York, N.Y. -- Science. 1989 Jul 7;245(4913):66-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2544998" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Amino Acid Sequence ; Base Sequence ; Diabetes Mellitus, Type 2/*genetics ; *Genes ; Humans ; Insulin Resistance ; Molecular Sequence Data ; *Mutation ; Protein-Tyrosine Kinases/*genetics ; Receptor, Insulin/*genetics
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
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    Bionet bites the dust (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-07-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marx, J L -- New York, N.Y. -- Science. 1989 Jul 14;245(4914):126.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2749249" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; *Computer Communication Networks ; *Computer Systems ; *Information Systems ; *Molecular Biology ; National Institutes of Health (U.S.) ; United States
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
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    Mutations in a protein kinase C homolog confer phorbol ester resistance on Caenorhabditis elegans (1989)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1989-03-31
    Description: The tpa-1 gene mediates the action of tumor-promoting phorbol esters in the nematode Caenorhabditis elegans. A genomic fragment that constitutes a portion of the tpa-1 gene was cloned by Tc1 transposon tagging and was used as a probe to screen a nematode complementary DNA library. One of the isolated complementary DNA clones had a nucleotide sequence that predicts a polypeptide of 526 amino acids. The predicted amino acid sequence revealed that the predicted tpa-1 protein sequence is highly similar to protein kinase C molecules from various animals, including man.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tabuse, Y -- Nishiwaki, K -- Miwa, J -- New York, N.Y. -- Science. 1989 Mar 31;243(4899):1713-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Fundamental Research Laboratories, NEC Corporation, Kawasaki, Kanagawa, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2538925" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Caenorhabditis/*drug effects/genetics ; Cloning, Molecular ; Codon ; DNA/genetics ; DNA Restriction Enzymes ; Drug Resistance/genetics ; Genetic Markers ; Molecular Sequence Data ; Mutation ; Nucleic Acid Hybridization ; Phenotype ; Phorbol Esters/*pharmacology ; Protein Kinase C/*genetics ; Sequence Homology, Nucleic Acid
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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