1,721,018 research outputs found
Enantioselective Synthesis of (S)-(Ð)-5,5,5-Trifluoro-4-Hydroxy-2-Pentanone by Baker's Yeast Reduction.
No full textBaker's yeast reduces 1,1,1-trifluoro-2,4-pentanedione with high regio- and enantio-selectivity to give (S)-5,5,5-trifluoro-4-hydroxy-2-pentanone. The enantiomeric excess was determined by Mosher's method and the absolute configuration was established by correlation with ethyl (R)-(+)-4,4,4-trifluoro-3-hydroxybutanoate
Stereoselective synthesis and absolute configuration of (1 ' R,3R,4R)-4-acetoxy-3-(2 ',2 ',2 '-trifluoro-1 '-hydroxyethyl)-azetidin-2-one
No full textThe title compound 3, an intermediate in the synthesis of fluorocarbapenems, is obtained with high stereocontrol by the condensation of (R)-(+)-ethyl 4,4,4-trifluoro-3-hydroxybutanoate with N-trimethylsilyl cinnamylidenimine. X-Ray diffraction analysis of the condensation product and chemical correlations allowed the unambiguous determination of the absolute configuration. (C) 1998 Elsevier Science Ltd. All rights reserved
Sintesi di Composti Fluorurati Chirali di Interesse Biologico
No full textSono esaminati i primcipali metodi di riduzione stereoselettiva di composti carbonilici mediante lievito di fornaio, con particolare riguardo alla sintesi stereocontrollata di precursori di molecole a potenziale attività biologic
Progettazione, Sintesi ed Attività di Acidi 1-Acilamminoalcanboronici Inibitori di beta-Lattamasi
No full textStereoselective Synthesis of Fluorinated β-Aminoacids from Ethyl trans-N-Benzyl-3-Trifluoromethyl-Aziridine-2-Carboxylate
No full textTrans N-benzyl-3-trifluoromethyl-2-ethoxycarbonylaziridine 2a, easily obtainable in enantiopure form by CAl catalyzed enzymatic resolution, allowed the regio and stereoselective synthesis of fluorinated anti-alpha-functionalized -beta-aminoacids, such as trifluoroisoserinates ar trifluoro-beta-alanine, and trans 3-halo or 3-hydroxy-beta-lactams. Starting from the anantiomerically pure methyl analogue of the title compound, pure enantiomers of trifluoroisoserine can be obtained in high overall chemical yield. Absolute configurations of optically-pure beta-aminoacids were determined by chemical correlation
Candida Cylindracea Lipase Catalysed Hydrolysis of Methyl Aziridine 2-Carboxylates and 2,3-Dicarboxylates.
No full textN-substituted aziridine-2-carboxylates and 2,3-dicarboxylates have been resolved with good to excellent stereochemical purity by enzymatic hydrolysis catalyzed by lipase from Candida cylindracea
Stereochemical Control in Yeast Reduction of Fluorinated beta-Diketones
No full textThe presence of asdditives in baker's yeast reductions of fluorinated beta-diketones turns the stereochemistry of the reaction towards the (R) or (S) enantiomers of the corresponding ketols
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