Deracemisation of β-hydroxy esters using immobilised whole cells of Candida parapsilosis ATCC 7330: substrate specificity and mechanistic investigation
摘要:
Deracemisation of aryl substituted beta-hydroxy esters by immobilised whole cells of Candida parapsilosis ATCC 7330 gave > 99% ee and up to 75% yield of their corresponding (S)-enantiomers. Mechanistic investigation of the deracemisation reaction carried out using a deuterated substrate, ethyl 3-deutero-3-hydroxy-3-phenyl propanoate revealed that while the (S)-enantiomer remains unreacted the (R)enantiomer undergoes enantioselective oxidation to its corresponding ketoester, which on complementary enantiospecific reduction gives the (S)-enantiomer in high yield and % ee. (c) 2006 Elsevier Ltd. All rights reserved.
A Practical Method for the Reformatsky Reaction of Aldehydes
作者:Angshuman Chattopadhyay、Avinash Salaskar
DOI:10.1055/s-2000-6378
日期:——
Reformatsky reaction of aliphatic aldehydes has been performed successfully by the addition of BF3 · OEt2 to a stirred suspension of aldehyde, bromo ester and Zn dust in aqueous THF. For aromatic aldehydes, addition of benzoyl peroxide is also required to effect the reaction.
Optically active 3-aryl-3-hydroxyesters of high enantiomeric excess (80–92% e.e.) are obtained by the reduction of 3-aryl-3-oxoesters with lithiumborohydride which has been chirally modified with N,N′-dibenzoylcystine and t-butyl alcohol.