Takeaki Umemura

Preparation of optically active secondary alcohols by combination of enzymatic hydrolysis and chemical transformation

Abstract Several kinds of optically active secondary alcohols (S)-2, which are important intermediates of bioactive compounds, were prepared from the corresponding racemic acetate (±)-1 in high chemical and optical yields by combination of enzymatic hydrolysis and chemical transformation.

Preparation of an optically pure secondary alcohol of synthetic pyrethroids using microbial lipases

SummaryEnzyme-catalysed hydrolysis of esters of 4-hydroxy-3-methyl-2-(2-propynyl)-cyclopent-2-enone (HMPC) was examined for the preparation of the optically pure alcohol moiety of synthetic pyrethroids. Among microorganisms and lipases tested, some bacterial lipases hydrolysed the ester of HMPC with high enantioselectivity and high reaction rate. Arthrobacter lipase gave the optically pure (R)-HMPC at 50% hydrolysis in a two-liquid phase reaction system of water and the insoluble substrate. The hydrolysis proceeded even at a substrate concentration of 80w/v%. The enantioselectivity was not changed with the chain length of the acid moiety of the esters. By combination of the enzymatic resolution with a chemical inversion of the (R)-alcohol, an efficient proess was developed for the total conversion of racemic HMPC to (S)-HMPC, which is an important alcohol for preparation of an insecticidallyactive synthetic pyrethroid.

Preparation of (4S)-4-hydroxy-3-methyl-2-(2′-propynyl)-2-cyclopentenone by combination of enzymatic hydrolysis and chemical transformation

Abstract (4S)-4-Hydroxy-3-methyl-2-(2′-propynyl)-2-cyclopentenone ((S)-2), which is an important alcohol moiety of optically active pyrethroid insecticides, was prepared from the corresponding racemic acetate ((±)- 1 ) by the combination of enzymatic hydrolysis and chemical transformation in high chemical and optical yields.