Process for the preparation of substituted carboxylic esters

Details Process for the preparation of substituted carboxylic esters Process for the preparation of substituted carboxylic esters

2006-12-26

2006-12-26

Wilson, James O. (Department: 1626)

Chemistry: molecular biology and microbiology

Micro-organism, tissue cell culture or enzyme using process...

Preparing oxygen-containing organic compound

C435S136000, C560S129000

Reexamination Certificate

active

07153675

ABSTRACT:
A process for the preparation of 2(S)-alkyl-5-halogenpent-4-ene carboxylic esters by enzymatic hydrolysis, comprising the steps: a) enzymatic hydrolysis of racemic 2-alkyl-5-halogenpent-4-ene carboxylic esters in aqueous and alkaline medium in the presence of an esterase; b) isolation of 2(S)alkyl-5-halogenpent-4-ene carboxylic esters by extraction with an organic solvent; c) isolation of 2(R)-alkyl-5-halogenpent-4-ene carboxylic acids from the aqueous-alkaline medium; d) Esterification of 2(R)-alkyl-5-halogenpent-4-ene carboxylic acids, e) subsequent racemization to form 2-alkyl-5-halogenpent-4-ene carboxylic esters; and f) return of the racemate obtained in step e) to step a), if necessary together with fresh racemic 2-alkyl-5-halogenpent-4-ene carboxylic esters. The process permits the undesired R-stereoisomers to be converted into the desired 2(S)-alkyl-5-halogenpent-4-ene carboxylic esters to avoid waste product from the synthesis.

REFERENCES:
patent: 6406912 (2002-06-01), Holla
patent: 6777574 (2004-08-01), Herold et al.
patent: 96 40975 (1996-12-01), None
patent: 99 45133 (1999-09-01), None
patent: 01 09083 (2001-02-01), None

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