Stereoisomere Aromastoffe XIX: Asymmetrische Reduktion von 4(5)-Oxocarbonsäuren mit Bäckerhefe / Asymmetric Reduction of 4(5)-Oxocarboxylic Acids by Baker's Yeast

Abstract

Asymmetric reduction of 4(5)-oxocarboxylic acids (esters) by baker's yeast and cyclization in acidic media yields optically active gamma(delta)-lactones. The evaluation of their chirality and optical purity was carried out by HPLC (HRGC) analysis of the corresponding 1,4(1,5)-diols via diastereomeric esters with (R)-Mosher acid (MTPA) and (S)-O-acyllactic acids respectively. By increasing the 4(5) alkyl side chain 4R(5R) configurated gamma(delta)-lactones with high ee-values are generated.