Novel baker's yeast catalysed hydride reduction of an epoxide moiety

Abstract

The preparation of 2-[2H]-l-(p-nitrophenyl)-1,2-epoxyheptan-3-one and its subsequent reduction by baker's yeast to the 2,3-diol is described. The mechanism of the reduction of the epoxide was determined using the B-2H isotope shift in 3C n.m.r, and mass spectroscopy and appears to be due to a novel enzyme catalysed hydride transfer from cofactors such as NADH or NADPH. No example of an enzyme catalysed hydride opening of an epoxide has been reported in the literature. The stereochemical implications of the hydride reduction are currently under investigation. A typical procedure for the baker's yeast reaction was carried as follows: The epoxy ketone (0.3 g) was added to actively fermenting yeast (4.0 g), sucrose (6.0 g) and water (30 ml) at 30 C. After 24hrs a further aliquot of sucrose was added and after 48hr the total mass was continuously extracted with chloroform.