ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Organic Chemistry  (8)
  • 1990-1994  (8)
  • 1980-1984
  • 1970-1974
  • 1940-1944
  • 1935-1939
  • 1990  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Enzyme-Mediated Regioselective Acylations of Flavonoid Disaccharide Monoglycosides (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 1837-1844 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flavonoid disaccharide monoglycosides have been acylated by the catalytic action of the protease subtilisin in anhydrous pyridine. The effects of the nature of the sugars and of the interglycosidic bonds on the regioselectivity of the reactions have been analyzed. The selectivity was excellent with rutin (1), hesperidin (2), naringin (6), and quercetin 3-O-[O-(β-D-glucopyranosyl)-(1→4)-α-L-rhamnoside] (9), giving single monoesters on their glucose moieties (see la, 2a, 6a, and 9b, resp.); quite interestingly, in the last compound, acylation did not occur at the free primary OH group but at the secondary OH—C(3‴). On the other hand, a mixture of mono- and diesters was obtained with the flavonoid peltatoside (7).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730705
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and Chemical Transformations of 4, 5-Homosnoutene Derivatives: An Attempted New Access onto the (CH)12 Energy Hypersurface (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 1182-1196 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacyclo[6. 4. 02, 4. 03, 10. 07, 9]dodeca-5, 11-diene(4) is proposed as new potential precursor of the truncated tetrahedrane 1. The synthesis of several new pentacyclo[5. 4. 0. 02, 4. 03, 9. 06, 8] undec-10-ene (4, 5-homosnoutene) derivatives including homosnouten-5-one(10), 5-methylidenehomosnoutene(19a) as well as homosnoutene-5-carb-aldehyde(17b) and their reactions directed toward ring enlargement to the skeleton of 4 are reported. Although all the homosnoutenes resisted ring expansions, several unexpected new polycyclic systems were obtained. Any intermediate developing a cationic center at C(5) of the skeleton of 10 rearranged with release of strain and opening of one or both three-membered rings to give compounds such as 22 and 23. The aminomethyl derivatives 13a and 13b, upon diazotation, underwent a remarkable fragmentation to give 10 and homosnouten-5-o1(20), respectively. The 5-(dibromomethyl) homosnouten-5-o1(14), upon treatement with t-BuLi, rearranged to the pentacyclic ether 15, while the carbine 11b, generated by the thermal or photochemical decomposition of the tosylhydrazone salt of 17c, solely gave 19a by C, H insertion. The 1, 1-dicyclopropylethene unit in 19c was excited selectively upon irradiation, but the products 26 and 27 of this photochemical rearrangement were derived only from n-participation in diradical intermediates 25a-25c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730506
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 2225-2241 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The irreversible-reduction potentials of 26 alkylcob(III)alamins (RCblIII 1a-z) and 26 alkylcob(III)yrinates (R‘Cby’III; 2a-z) (Ep 1a-z and Ep 2a-z, resp.) have been measured in situ by single-scan voltammetry of hydroxocob(III)alamin hydrochloride (vitamin B12b- HCl; 1) or heptamethyl cob(II)yrinate perchlorate (ClO4‘Cby’II; 2) in presence of the corresponding alkyl halides (RX;3a-z) in DMF. The reduction potentials of alkylcobalt complexes exhibiting half-life times as short as a few seconds become measurable by this technique. Thermodynamic cycles prove that the observed reduction potentials are closely related to the standard reduction potentials E°(R—CoIII + e-⇆R⋅ + CoI). Electron-withdrawing groups and/or an increased degree of substitution at the Co-bound C-atom in RCblIII and, R‘Cby’III shift Ep(1a-z) and Ep (2a-z) towards positive potentials. Linear correlations have been found between Ep(1a-z) (Ep(2a-z)) of RCblIII (R‘Cby’III) and the pKa of RH (or the Taft σ*- or the Hammett σp--values of R) within each class of R, i. e. MeCblIII (Me‘Cby’III), primary RCblIII (R‘Cby’III) and secondary RCblIII (R‘Cby’III). The correlations allow to distinguish between electronic effects of the Co-bound alkyl residues and their steric interactions with the corrin side chains. The correlations have further been used to visualize the light-induced formal insertion of an olefin into the Co, C-bond of an alkylcobalamin (Scheme 2, 1a→1u), a key step in the vitamin-B12-catalized C, C-bond formation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730820
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Concentration-dependent deuterium isotope effects on the quantum yield of arene-alkene meta photocycloaddition: The role of excimers (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 273-278 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A deuterium isotope effect on the arene-alkene meta photocycloaddition, reported earlier for toluene/toluene-d8 photoaddition to cyclopentene, was found to depend on the concentration of both arene and alkene. This phenomenon is explained in terms of an unbalanced dissociation of ‘mixed’ excimers, which play a role in the intermolecular competition experiments.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030411
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    [4]Paracyclophane: MNDO and STO-3G molecular structure and strain energyTaken in part from Ref. 1. (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 295-300 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structure of [4]paracyclophane was optimized at the semiempirical MNDO and the ab initio STO-3G level. A comparison of the results showed that the benzene ring is much less bent at the STO-3G level. Although some bond alternation is predicted at both levels of theory, the aromatic carbon-carbon bond lengths are still in the range typical of highly delocalized compounds. The calculated strain energy [SE(tot.)] of [4]paracyclophane is larger for the STO-3G structure. Nevertheless, the distributions of SE(tot.) over the bent benzene ring [SE(bb.)] and the oligomethylene bridge [SE(br.)] are the same for the MNDO and STO-3G structures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030505
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Structure of 1,2,6-thiadiazine 1,1-dioxides (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 470-476 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ab initio theoretical calculations were carried out on the three tautomers, NH, OH and CH, of 1,2,6-thiadiazine 1,1-dioxides. Different basis sets were employed in order to obtain an adequate description of these cyclic sulphamide derivatives. A coherent picture is obtained which includes relative stability of tautomers (NH 〉 CH 〉 OH), non-planarity of NH and CH tautomers and electronic distribution (Boys' localized orbitals).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030709
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Lone-pair charges and structural effects (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 255-259 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lone-pair charge, Qlpf, of a base B is a (theoretically calculated) measure of the amount of charge on the lone pair of B that binds to an acid Av (v = 0, 1) in an acid-base reaction. It is shown how they can be used for the quantitative study of structural effects on gas-phase proton affinities, vertical ionization potentials and hydrogen-bonding basicities.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030408
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Synthesis, characterization and in vitro antitumour activity of a series of substituted 2,2-di-n-butyl-4-oxo-benzo-1,3,2-dioxastannins (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 4 (1990), S. 335-343 
    Details
    ISSN: 0268-2605
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characterization by 1D and/or 2D 1H NMR, 13C NMR, 119Sn NMR, Mössbauer and mass spectrometry of a series of di-n-butyltin derivatives of 3-, 4-, and 5-methyl-, 3-, 4-, and 5-methoxy-, 4- and 5-amino-substituted, and 3,5-diiodo-salicyclic acids is described. Their NMR spectra suggest that they are present as dimers in CDCl3 solution, like the di-n-butyltin derivative of unsubstituted salicyclic acid. This has been confirmed by the observation of mixed dimers. The insoluble derivatives have been characterizerd by solid state cross polarization/magic angle spinning (CP/MAS) 13C and/or 119Sn NMR, Mössbauer and mass spectroscopy. These compounds are characterized in vitro by a lower inhibition dose than cis-platin or etoposide against a series of five human cell lines.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590040406
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...