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Titolo:
Biocatalytic reduction of beta,delta-diketo esters: A highly stereoselective approach to all four stereoisomers of a chlorinated beta,delta-dihydroxyhexanoate
Autore:
Wolberg, M; Hummel, W; Muller, M;
Indirizzi:
KFA Julich GmbH, Forschungszentrum, Inst Biotechnol 2, D-52425 Julich, Germany KFA Julich GmbH Julich Germany D-52425 echnol 2, D-52425 Julich, Germany Univ Dusseldorf, Inst Enzymtechnol, D-52426 Julich, Germany Univ Dusseldorf Julich Germany D-52426 mtechnol, D-52426 Julich, Germany
Titolo Testata:
CHEMISTRY-A EUROPEAN JOURNAL
fascicolo: 21, volume: 7, anno: 2001,
pagine: 4562 - 4571
SICI:
0947-6539(20011105)7:21<4562:BROBEA>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
HMG-COA REDUCTASE; STEP ASYMMETRIC-SYNTHESIS; BETA-HYDROXY KETONES; RU-BINAP COMPLEX; ENANTIOSELECTIVE SYNTHESIS; DIASTEREOSELECTIVE REDUCTION; CONVERGENT SYNTHESIS; ADDITION-REACTIONS; CHIRAL SULFOXIDES; BAKERS-YEAST;
Keywords:
alcohols; asymmetric catalysis; enzymes; ketones; reduction;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
74
Recensione:
Indirizzi per estratti:
Indirizzo: Muller, M KFA Julich GmbH, Forschungszentrum, Inst Biotechnol 2, Postfach 1913, D-52425 Julich, Germany KFA Julich GmbH Postfach 1913 Julich GermanyD-52425 h, Germany
Citazione:
M. Wolberg et al., "Biocatalytic reduction of beta,delta-diketo esters: A highly stereoselective approach to all four stereoisomers of a chlorinated beta,delta-dihydroxyhexanoate", CHEM-EUR J, 7(21), 2001, pp. 4562-4571

Abstract

A stereoselective chemoenzymatic synthesis of all four stereoisomers of tert-butyl 6-chloro-3,5-dihydroxyhexanoate (6a) is presented. The key step ofthe sequence is a highly regio- and enantioselective single-site reductionof tert-butyl 6-chloro-3,5-dioxohexanoate (1 a) by two enantiocomplementary biocatalysts. Alcohol dehydrogenase from Lactobacillus brevis (recLBADH) afforded a 72% yield of enantiopure tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate [(S)-2a]. The enantiomer (R)-2a was prepared with 90-94% ee by Baker's yeast reduction in a biphasic system (50% yield). Both biotransformations were performed on a gram scale. The P-keto group of the enantiomeric delta -hydroxy-beta -keto esters 2a thus obtained was reduced by syn- and anti-selective borohydride reductions. Permutation of the reduction methods yielded all four stereoisomers of the crystalline target compound 6a (greater than or equal to 99.3% ce, dr greater than or equal to 205:1), which is aversatile 1,3-diol building block. recLBADH accepts a variety of beta,delta -diketo esters as was determined in a photometric assay. tert-Butyl 3,5-dioxohexanoate (1b) and tert-butyl 3,5-dioxoheptanoate (1c) were reduced on a preparative scale as well to afford the corresponding delta -hydroxy-beta-keto esters (R)-2b and (R)-2c with 99.4% ee and 98.1 % ee, respectively.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/04/20 alle ore 02:48:52