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  • 1
    Electronic Resource
    Electronic Resource
    Polymer-supported chiral diol as ligand of Ti(IV) for enantioselective Diels-Alder reaction (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 191-197 
    Details
    ISSN: 0899-0042
    Keywords: TADDOL ; titanium complexes ; chiral Lewis acid ; polymer-supported ; polystyrene-divinylbenzene ; enantioselective ; Diels-Alder ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the first polymer-supported TADDOL is reported. Its efficiency as chiral ligand of Ti(IV) was studied in the Diels-Alder cycloaddition of cyclopentadiene to 3-crotonoyl-1,3-oxazolidin-2-one, and was superior to that observed for its homogeneous equivalent. (4R,5R)-α,α,α′,α′-2-pentaphenyl-4,5-dimethanol-1,3-dioxolane. Recycling of the heterogeneous Ti(IV)-TADDOLate was also studied, being the most suitable method for the repreparation of the catalyst from the ligand after use. Chirality 9:191-197, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Degradation and racemization of zopiclone enantiomers in plasma and partially aqueous solutions (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 267-271 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; cyclopyrrolone ; isomers ; racemization ; stability ; zopiclone ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We investigated the degradation and racemization of zopiclone (ZOP) enantiomers in plasma and partially aqueous solutions (ethanol:phosphate buffer). Degradation and racemization increased with increasing pH and temperature. Degradation products were identified by means of mass spectrometry, which revealed hydrolysis of the carbamate function and opening of the pyrrolidone ring. In plasma, neither degradation nor racemization occurred after 6 months of storage at -20°C and subsequent extraction. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530070413
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  • 3
    Electronic Resource
    Electronic Resource
    Carbenoid Reactions in Rhodium(II)-Catalyzed Decomposition of Iodonium Ylides (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 947-958 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intermediacy of metallocarbenes in decomposition reactions of iodonium ylides with [Rh2(OAc)4] was established by comparison with reactions of the corresponding diazo compounds. The sensitivity of the RhII-catalyzed intermolecular cyclopropane formation from substituted styrenes and bis(methoxycarbonyl)(phenyliodono)methanide (1a) or dimethyl diazomalonate (1b) is identical. The Hammett plot (with σ+) has a slope of -0.47. Iodonium ylides and diazo compounds afford the same products in [Rh2(OAc)4]-catalyzed cyclopropane formations, cycloadditions, and intramolecular CH insertions, and exhibit the identical selectivity in intramolecular competitions for cyclopropane formation and insertion. The intramolecular CH insertion of the ylide 20c, when carried out in the presence of a chiral catalyst ([Rh2{(-)-(S)-ptpa}4]), results in formation of 21a having an ee of 67%, identical to the ee obtained with the diazo compound 20b.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780417
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  • 4
    Electronic Resource
    Electronic Resource
    Syntheses of Chiral Menthyl and Neomenthyl Sulfides, sulfoxides and sulfones (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 538-541 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempts to synthesize stereospecifically menthanethiol (2) and menthyl thiocyanate (3) from suitable electrophilic neomenthyl substrates (4a-c), and a variety of sulfur nucleophiles failed or predominantly led to β-elimination products. Almost quantitative yields of mixtures of 2 and its 3-epimer (8) were obtained by reductive cleavage of (-)-3-menthone ethylene dithioacetal (7), but stereoselectivity was low (ratio of 2/8, 41:59) and the mixture could not be resolved. Recrystallization and subsequent oxidation of the dinitrophenyl sulfides of 2 and 8 allowed the isolation of the dinitrophenyl menthyl and neomenthyl sulfoxides (12 and 13, respectively), and an irresolvable mixture of the sulfones 14 and 15.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.199533701115
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of Thromboxane A2 Models from Glucose. II. Epoxidation Studies of Hex-2-enopyranosides (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1983-1987 
    Details
    ISSN: 0947-3440
    Keywords: Thromboxane model compounds ; Carbohydrates ; Epoxidations ; Glycosides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of halohydrin 7, a potential precursor of the heterocyclic moiety of thromboxane A2 (TXA2) is described. Claisen-Meerwein-Eschenmoser rearrangement of hex-3-enopyranosides 4 and 8 yields the branched olefin sugars 5 and 9. Epoxidation studies with perbenzimidic acid (Payne's method) and m-chloroperbenzoic acid (Anderson's method) were performed. Under treatment of the 2,3-anhydrosugar 6 with LiBr, the epimeric halohydrins 7 and 10 were obtained in a ratio of 3:2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970926
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and Reaction of Some 2-Alkylene-1,3-oxazolidines (1998)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 340 (1998), S. 178-180 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from 1,3-oxazoline 6 synthesis of ketene-O,N-acetals 2b, 2c is described via NBS bromination and HBr elimination.The N-sulfonyl-oxazolidines 10, 11 are synthesized by cyclization starting from aminoalcohol 7, 10d react with potassium t-butoxide to the oxazolidine 2d; 11d gives under the some conditions the ring opening product 12d, compound 10a is inert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19983400213
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  • 7
    Electronic Resource
    Electronic Resource
    Formaldehyde SAMP-Hydrazone - a neutral chiral formyl anion and cyanide equivalent (1998)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 340 (1998), S. 281-285 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19983400315
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  • 8
    Electronic Resource
    Electronic Resource
    Substituted metallotriazolehemiporphyrazines: Synthesis and characterization by FAB-MS (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 495-499 
    Details
    ISSN: 0947-3440
    Keywords: Metallotriazolehemiporphyrazines ; Phthalocyanines ; Hemiporphyrazines ; Electrical conductivity measurements ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel triazolehemiporphyrazines 3a, 4a, and 5a, substituted on the isoindole units and soluble in organic solvents, have been synthesized by condensation of 3,5-diamino-1,2,4-triazole with the corresponding 1,3-diiminoisoindoline. First-row transition-metal complexes 3b-e, 4b-e, and 5b-e have also been prepared by reaction of the free ligands 3a, 4a, and 5a with the appropriate metal(II) salt. A FAB mass spectrometric study of this kind of metallomacrocycles is reported. Triazolehemiporphyrazines 3-5 show electrical conductivities in the range of 10-12-10-9 Scm-1.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950368
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