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  • Cyclizations  (19)
  • Wiley-Blackwell  (19)
  • American Chemical Society
  • American Meteorological Society
  • 2015-2019
  • 1995-1999  (19)
  • 1980-1984
  • 1975-1979
  • 1999  (19)
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  • Wiley-Blackwell  (19)
  • American Chemical Society
  • American Meteorological Society
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  • 2015-2019
  • 1995-1999  (19)
  • 1980-1984
  • 1975-1979
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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of 1β-Methylcarbapenem Antibiotic Precursors by Cyclization Using π-Allylpalladium Complexes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 621-626 
    Details
    ISSN: 1434-193X
    Keywords: 1β-Methylcarbapenems ; Palladium ; Ruthenium ; Catalysis ; Cyclizations ; Stereoselective hydrogenation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -An efficient diastereoselective multi-step synthesis of bicyclic 1β-methylcarbapenem antibiotic precursors has been developed, starting from the commercially available 4-acetoxyazetidin-2-one 4. Chiral ruthenium catalysts are used in the hydrogenation step to control the β-stereochemistry at the 1-position, and a π-allylpalladium ring-closure strategy is used to form the functionalized carbapenem skeleton.
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  • 2
    Electronic Resource
    Electronic Resource
    The Electrocyclic Reactions (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1921-1924 
    Details
    ISSN: 1434-193X
    Keywords: Cyclizations ; Electrocyclic reactions ; Solvent effects ; Salt effect ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants of the electrocyclic ring closure of (1Z,3Z,5E)-1,2,6-triphenylhexa-1,3,5-triene (1) and of the ring opening of dimethyl 3,4-dimethyl-1,2-diphenylcyclobutene-cis-3,4-dicarboxylate (3) were determined in 15 and 16 solvents, respectively. The ring closure of 1 shows, in spite of theoretical predictions, neither solvent nor salt effects. For the ring opening of 3, small solvent and salt effects were found, suggesting the possibility of observing small acceleration due to specific solute-solvent or salt interactions.
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  • 3
    Electronic Resource
    Electronic Resource
    Radical Cyclizations - Synthesis of γ-Lycorane (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1925-1933 
    Details
    ISSN: 1434-193X
    Keywords: γ-Lycorane ; Radicals ; Cyclizations ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-γ-Lycorane has been synthesized in ten steps from piperonylic alcohol. Two radical reactions were used successively to build the D and B rings. A formal synthesis of (+)-γ-lycorane was achieved via an optically active unsaturated aldehyde intermediate.
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  • 4
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    Electronic Resource
    Iodocyclisation of 1,4-Dihydropyridines; Synthesis and Reactivity of 1-Iodoindolo[2,3-a]quinolizidines (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2997-3003 
    Details
    ISSN: 1434-193X
    Keywords: Alkaloids ; Cyclizations ; Iodine ; Nitrogen heterocycles ; Oxidations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of iodine (or related species) to β-acyl-N-alkyl-1,4-dihydropyridines 1, which possess an N-substituent with an appropriate nucleophile moiety, leads to the corresponding 3-iododihydropyridinium ions, which undergo an internal nucleophilic attack to give, regio- and stereoselectively, the iodobi(poly)heterocyclic ring systems 2a-f in good yields. Reactivity studies on the iodoindoloquinolizidines 2e,f lead to the pentacyclic cyclopropane systems 4a,b, azides 5 and 6, norderivative 9 and, by a base-induced elimination, dihydropyridine 10, a precursor of the zwitterionic alkaloids flavopereirine and 6,7-dihydroflavopereirine.
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  • 5
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    Palladium(0)-Catalyzed Synthesis of 2-Vinyl-2,3-dihydro-benzo[1,4]dioxins (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2665-2673 
    Details
    ISSN: 1434-193X
    Keywords: 2-Vinyl-2,3-dihydro-benzo[1,4]dioxins ; Cyclizations ; Palladium ; Chirality ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 1,4-bis(methoxycarbonyloxy)but-2-ene (2a-3a) or 3,4-bis(methoxycarbonyloxy)but-1-ene (4a) with various substituted benzene-1,2-diols was catalyzed by a palladium(0) complex to give substituted 2-vinyl-2,3-dihydro-benzo[1,4]dioxins in good yields via a tandem allylic substitution reaction. In the case of 4-substituted benzene-1,2-diols, the ratio of regioisomers is determined by the relative acidity of the two phenolic protons. For 3-substituted benzene-1,2-diols, this ratio is determined only by steric effects in the case of alkyl substituents, although it is determined mainly by the relative stabilities of the corresponding phenates for other substituents; however, for 3-nitrobenzene-1,2-diol, this ratio is determined by the relative leaving-group ability of 2-nitro- or 3-nitrophenate. When the cyclisation was performed in the presence of an optically active phosphane, chiral 2-vinyl-2,3-dihydro-benzo[1,4]dioxin (5) was obtained with enantioselectivity of up to 45% using BINAP as the chiral phosphane.
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  • 6
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    Rearrangements and Cyclizations of 2-Chloropropenyl-Appended Indolo[2,3-a]quinolizidine Derivatives (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3429-3432 
    Details
    ISSN: 1434-193X
    Keywords: Cyclizations ; Allylic rearrangement ; Indoloquinolizidine ; Apovincamine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alcohols 4a,bderived from ketone 3 were transformed, in acidic medium, to the rearranged compounds 6 (or 6′) and to the pentacyclic derivative 8. This procedure provides easy access to the 16-deethylapovincamine skeleton.
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  • 7
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    Electronic Resource
    Synthesis of 3,4-Dihydro-2H-pyrido[1,2-b]isoindol-1-one and 3,4-Dihydro-2H-pyrido[1,2-b]pyrrolidin-1-one Functionalized at the C-6 Position by an Intramolecular Horner-Wadsworth-Emmons Reaction (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3489-3493 
    Details
    ISSN: 1434-193X
    Keywords: Methylene-1,1-bisphosphonate ; 3-Bromoalkylimide ; Horner-Wadsworth-Emmons reaction ; Phosphonate complexes ; Heterocyclic compounds ; Cyclizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel polyheterocycles were prepared from a new annellation reaction which proceeds by nucleophilic substitution followed by an intramolecular Horner-Wadsworth-Emmons reaction between imides and β-functionalized phosphonates.
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  • 8
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    Syntheses, Structures, and Reactions of C-Methoxycarbonyl-Functionalized Small- and Medium-Sized P-Heterocycle Complexes (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1567-1579 
    Details
    ISSN: 1434-1948
    Keywords: Phosphorus heterocycles ; 2H-Azaphosphirene complexes ; Water-soluble P ligands ; Tungsten ; Cyclizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal ring-opening of [{2-bis(trimethylsilyl)methyl-3- phenyl-2H-azaphosphirene-ĸP}pentacarbonyltungsten(0)] (8a) in the presence of dimethyl acetylenedicarboxylate (DMAD) led to the 2,3-bifunctionalized 1H-phosphirene complex 9a and the 4-phenyl-substituted 2H-1,2-azaphosphole complex 10a, the latter as a by-product. If a small amount of benzonitrile was added, complex 10a was obtained as the main product, along with a small amount of the decomplexed 2H-1,2-azaphosphole 11, which could not be isolated. Reaction of complex 10a with elemental sulfur furnished the corresponding PV sulfide 13. When the ring-opening of complex 8a was performed in the presence of two equivalents of DMAD and two equivalents of dimethyl cyanamide, we obtained the 4-dimethylamino-substituted 2H-1,2-azaphosphole complex 10b, together with the diastereomeric Δ3-1,3,2-oxazaphospholene complexes 14a,b. On reaction of [{2-pentamethylcyclopentadienyl-3-phenyl-2H-azaphosphirene-ĸP}pentacarbonyltungsten(0)] (8b) and DMAD in toluene, the corresponding 1H-phosphirene complex 9b was only formed as a transient species and the P-coordinated P,C-cage compound 15 was the final product. Using benzonitrile as solvent, the 4-phenyl-substituted 2H-1,2-azaphosphole complex 10c was obtained, together with the 7-aza-1-phosphanorbornadiene complex 16, the latter through partial decomposition of 10c coupled with rearrangement and a Diels-Alder reaction; the ratio 10c/16 was found to depend strongly on the molar ratio of complex 8b to DMAD. A cycloaddition reaction of the 2,3-bifunctionalized 1H-phosphirene complex 9a with 2,3-dimethylbutadiene furnished the bicyclic phosphirane complex 19, along with a small amount of the noncoordinated bicyclic phosphirane 20. Reaction of complex 9a with diethylamine yielded the phosphirane complex 21 as a 1,2-addition product, the diorganophosphane complex 22 through ring-opening of 9a, and the 3,4-functionalized 1,2-dihydro-1-phosphet-2-one complex 23 through an unprecedented ring-expansion reaction; the products 21, 22, 23 were formed in a ratio of ca. 1:1:1. The structures of the 1H-phosphirene complex 9a, the 4-dimethylamino-substituted 2H-1,2-azaphosphole complex 10b, the bicyclic phosphirane complex 19, the phosphirane complex 21, and the 1,2-dihydro-1-phosphet-2-one complex 23 have been determined by single-crystal X-ray diffraction analysis.
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  • 9
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    Reactions of 1,8-Diheterocyclotetradeca-4,11-diynes with (η4-Cycloocta-1,5-diene)(η5-cyclopentadienyl)cobalt (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 499-504 
    Details
    ISSN: 1434-1948
    Keywords: Alkynes ; Heterocycles ; Cyclizations ; Cobalt ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The following monocyclic and bicyclic 14-membered diynes were treated with [CpCo(cod)]: 1-oxacyclotetradeca-4,11-diyne (2), 1,8-dioxacyclotetradeca-4,11-diyne (3), cyclotetradeca-4,11-diynone (4), cyclotetradeca-4,11-diyne-1,8-dione (5), 1,1,8,8-tetramethyl-1,8-disilacyclotetradeca-4,11-diyne (6), 1-allyl-1-azacyclotetradeca-4,11diyne (7), 1,8-dipropyl-1,8-diazacyclotetradeca-1,11-diyne (8), 1,8-diallyl-1,8-diazacyclotetradeca-4,11-diyne (9), 1,8-diazabicyclo[6.6.4]octadeca-4,11-diyne (10), 1,8-diazabicyclo[6.6.6]eicosa-4,11-diyne (11), 1,10-diazabicyclo[8.6.6]docosa-13,19-diyne (12) and 1,12-diazabicyclo[10.6.6]tetracosa-15,21-diyne (13). In all cases we obtained an intramolecular cyclobutadiene complex stabilized with a CpCo fragment (15-26). For 3 we could isolate, besides the cyclobutadiene complex 16, the trimerization product 28. In the cases of 15, 16, 18, 20, 23, 25, and 26 the structure of the cylobutadiene complexes could be confirmed by X-ray studies. Common to all structures is a boat-like conformation of the tricyclic unit containing the cyclobutadiene ring. The two cycloheptene units adopt a chair conformation in which the heteroatom is removed from the metal center.
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  • 10
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    Unprecedented Formation of a Benzo[d]azepine by Acid-Catalyzed Cyclization of a Camphor-Derived N-Formylenamine (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 519-522 
    Details
    ISSN: 1434-193X
    Keywords: Enamides ; Diformamides ; Cyclizations ; Nitrogen heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A convenient synthesis of (-)-N-styryl-N-[2-(1,7,7-trimethylbicyclo[2.2.1]hept-2-enyl)ethyl]formamide (2) was developed starting from natural (+)-camphor (3) via (-)-2-(bornen-2-yl)ethanol (6). Cyclization of the N-formylenamine 2 with the aid of 9-borabicyclo[3.3.1]non-9-yl triflate yielded a methanobridged octahydro-1H-benzo[d]azepine derivative.
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  • 11
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    Thermal Isomerisation of Substituted Semibullvalenes and Cyclooctatetraenes - A Kinetic Study (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 813-822 
    Details
    ISSN: 1434-193X
    Keywords: Cyclizations ; Hydrocarbons ; Isomerizations ; Kinetics ; Polycycles ; Rearrangements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Whereas 1,5-dimethylsemibullvalene (1b) equilibrates with 1,5-dimethylcyclooctatetraene (2b), the semibullvalene-2,6-dicarbonitriles 13 rearrange irreversibly to afford mixtures of the isomeric cyclooctatetraene-1,5-dicarbonitriles 14 and 15. Arrhenius and Eyring parameters of these thermal isomerisation reactions have been determined for the gas phase (1b → 2b) and [D6]benzene solutions (1b → 2b, 13 → 14 + 15). Furthermore, the activation parameters of the known rearrangement of octamethylcyclooctatetraene (3) to octamethylsemibullvalene (4) have been determined. - The data for these compounds, together with those for related compounds previously reported in the literature, show that substituents not only influence the relative stabilities of the semibullvalene and cyclooctatetraene systems but also the height of the energy barrier for their interconversion. Those substituents that lower the barrier toward the degenerate Cope rearrangement of semibullvalenes simultaneously accelerate their rearrangement to cyclooctatetraenes thus limiting the thermal stability of the former.
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  • 12
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    EPC Syntheses of Trifluorocitronellol and of Hexafluoropyrenophorin - A Comparison of Their Physiological Properties with the Nonfluorinated Analogs (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2533-2544 
    Details
    ISSN: 1434-193X
    Keywords: (S)-4,4,4-Trifluoro-3-hydroxybutanoic acid ; 2-Trifluoromethyl-3-hydroxypropanoic acid (F3-Roche acid) ; Chiral CF3-containing synthetic building blocks ; Natural products ; Cyclizations ; Olfactory comparison ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The natural products pyrenophorin (1a) and citronellol (2a), in which CH3 groups are replaced by CF3, were synthesized in enantiomerically pure form from simple four-carbon trifluorohydroxy acids (obtained by resolution). The cyclizations of analogous CH3 and CF3 seco acids (cf. 9) to give pyrenophorin derivatives require different methodologies; the F6 derivative 10a could be obtained in only very poor yield; in contrast to pyrenophorin. Most surprisingly, F6-pyrenophorin (1d) has an extremely poor solubility in common organic solvents, and has essentially no antimicrobial activity (see Table 2). The synthesis of F3-citronellol is the first application of an enantiopure F3-Roche acid (12) as a synthetic builiding block (see its derivatives 17-23). An olfactory comparison of F3-citronellol [(R)-(+)-2b] with citronellol and ent-citronellol (Scheme 6) shows that the fluorine derivative has a “very metallic, aggressive” character and lacks totally the “sweetness” of (R)-(+)- and (S)-(-)-2a. A number of generally useful, CF3-substituted electrophilic (iodides 4, 18, 37, tosylates 19, 33, aldehydes 5, 29, 39) and nucleophilic (Li dithiane precursor of 5, Li compounds 20, 38) reagents are described for the first time.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/1999/99137_s.pdf or from the author.
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  • 13
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    A Versatile Synthetic Method for Preparing 1,2,3,5-Tetrasubstituted Pyrroles Using Isothiocyanates and 2-Alkynyl Ethers or 2-Alkynylamines as Building Units (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2663-2664 
    Details
    ISSN: 1434-193X
    Keywords: Metallations ; Copper ; Homogeneous catalysis ; Cyclizations ; Regioselectivity ; Azatrienes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fundamentally new approach for the construction of pyrrole rings is exemplified by highly efficient one-pot syntheses of 1,2,3,5-tetrasubstituted pyrroles starting from alkyl isothiocyanates and 2-alkynylamines or 2-alkynyl ethers.
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  • 14
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    Optically Pure 3,6-Dioxazocan-2-one Derivatives by Intramolecular Cycloaddition of Azidoformates and their Opening to Substituted α-Amino Ketones (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2709-2711 
    Details
    ISSN: 1434-193X
    Keywords: Aminations ; Azides ; Cyclizations ; Nitrogen heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Azidoformates derived from chiral enol ethers, when irradiated, give 3,6-dioxazocan-2-one derivatives 7 by a highly diastereoselective intramolecular cycloaddition. The hydrolysis of 7 gives a single derivative of 2-aminocyclohexanone.
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  • 15
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    Palladium-Catalyzed Hydrovinylation of Vinyl Triflates with Alkynes An Approach to the Synthesis of 3-Vinylfuran-2(5H)-ones (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3305-3313 
    Details
    ISSN: 1434-193X
    Keywords: Palladium ; Hydrovinylation ; Cyclizations ; Furan-2(5H)-ones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of alkynes with vinyl triflates in the presence of catalytic amounts of Pd(OAc)2 and HCOOK, omitting phosphane ligands, affords hydrovinylation products usually in good to high yields. The reaction has been employed to develop a regioselective synthesis of 3-vinylfuran-2(5H)-ones from methyl 4-hydroxy-2-butynoates.
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  • 16
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    A New Generation of Alkoxyl Radical Precursors - Preparation and Properties of N-(Alkoxy)-4-arylthiazole-2(3H)-thiones (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1275-1290 
    Details
    ISSN: 1434-193X
    Keywords: Alkoxyl radical ; Cyclizations ; Radicals ; Tetrahydrofuran ; Thiazolethione ; Thiazolethione ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -N-(Hydroxy)thiazole-2(3H)-thiones 6-10 have been prepared in a short and efficient synthesis from p-substituted acetophenones. Alkylation of heterocycles 6-10 in the form of their potassium or tetraalkylammonium salts 11-15 affords N-alkoxy-4-arylthiazole-2(3H)-thiones 16-20 in good to satisfactory yields. The hitherto unknown thiones 16-20 have been subjected to a detailed structural investigation (NMR spectroscopy and X-ray crystallography) and furthermore to a mechanistic study in order to explore their utility as sources of oxygen-centered radicals in solution. From the results of these studies, the following conclusions can be drawn: (i) X-ray analyses of the p-chlorophenyl-substituted acid 9, of the O-alkyl derivatives 19c, 19f, and of the O-mixed anhydride 19k indicate short C-S bonds [C2-S2 = 1.637(5)-1.684(2) Å] and long N-O connectivities [N3-O1 = 1.369(3)-1.379(2) Å] in the thiohydroxamate functionalities. Furthermore, O-alkyl- or O-acyl substituents at O1 are twisted out of the thiazolethione plane by ca. 90°, which points to lone-pair repulsion between nitrogen and oxygen atom as the underlying structural motif of the cyclic thiohydroxamate derivatives. (ii) Alkylation of ambidentate thiohydroxamate anions (salts 11-15; oxygen and sulfur nucleophiles) affords almost exclusively O-esters 16-20 (alkylation at the oxygen atom). (iii) Based on the results of X-ray diffraction studies and on the 1H- and 13C-NMR spectra, guidelines for the characterization of N-(alkoxy)thiazolethiones 16-20 and 2-(alkylsulfanyl)thiazole N-oxides 21-25, i.e. the products of S-alkylation of thiohydroxamate salts 11-15, could be derived. (iv) Photolyses of substituted N-(4-pentenoxy)-4-arylthiazolethiones 16-20 in general and in particular of p-chloro derivatives 19 were carried out in the presence of the hydrogen donor Bu3SnH, and afforded substituted tetrahydrofurans 31 or tetrahydropyrans 32 as major products in good yields. The observed stereo- and regioselectivities of ethers 31 and 32 point to alkoxyl radicals 30 as reactive intermediates, which add intramolecularly by selective 5-exo-trig or 6-endo-trig pathways to the olefinic double bonds. In terms of synthetic access and ease of handling of the radical precursors, the p-chlorophenyl-substituted thiazolethiones 9 and 19 exhibit significant advantages over all the other thiones used in this study and are considered as excellent substitutes for the pyridinethiones as efficient sources of free alkoxyl radicals. Consequently, the present compounds may be of use in both mechanistic and synthetic studies.
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  • 17
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    An Efficient Synthesis of 5-(or 6-)Arylbenzoindolizidine and -quinolizidine Derivatives (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2345-2352 
    Details
    ISSN: 1434-193X
    Keywords: Horner reaction ; Enamides ; Reductions ; Cyclizations ; Alkaloids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new methodology for the synthesis of (hetero)arylated benzoindolizidine and benzoquinolizidine derivatives through sequential reduction of pyrrolidine- and piperidine-based aromatic enamides, and ultimate cyclization, is reported.
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  • 18
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    Chiral Perfluoroalkyl-Substituted Hexahydrofuro[2,3-b]pyran Derivatives Based on a Carbohydrate Precursor (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2429-2432 
    Details
    ISSN: 1434-193X
    Keywords: Allyl glycosides ; Cyclizations ; Domino reactions ; Mesogens ; Perfluoroalkylations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (4′R)-4,6-Di-O-acetyl-1,2,3-trideoxy-3-iodo-4′-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecafluorononyl)-2′,3′,4′,5′-tetrahydro-α-D-glucopyranoso[1,2-b]furan (2) and its (4′S) diastereomer (3) were prepared by dithionite-mediated addition of 1-iodoperfluorooctane to allyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside (radical “domino reaction”). Subsequently, the major product [(4′R) form] was deprotected via 4 to the hexahydrofuro[2,3-b]pyran derivative 5, which was used as a fluorinated building block to prepare the nonamphiphilic chiral mesogens 6-8 by “Mitsunobu” etherification and 9 by esterification. The reagents used to transform 5 to 6-9 were 4-cyanophenol, 4-(4-cyanophenyl)phenol, 4-(4-heptyloxybenzoyloxy)phenol, and 4-heptyloxybenzoyl chloride.
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  • 19
    Electronic Resource
    Electronic Resource
    Selectivity in the Tandem Cyclization - Carboxylation Reaction of Unsaturated Haloaryl Ethers Catalyzed by Electrogenerated Nickel Complexes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1885-1891 
    Details
    ISSN: 1434-193X
    Keywords: Electrochemistry ; Carbon dioxide fixation ; Cyclizations ; Nickel ; Dihydrobenzofuran ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical reduction of a series of 2-haloaryl ethers containing allyl and propargyl groups under CO2 allows the synthesis of benzofuranacetic acid derivatives. This novel intramolecular cyclization-carboxylation reaction is carried out in single-compartment cells and is catalyzed by [Ni(cyclam)Br2].
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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