Reductive C2-homologation of substituted benzaldehydes by fermenting baker's yeast.

Abstract

Reduction of benzaldehyde and substituted benzaldehydes with actively fermenting baker's yeast afforded optically active 1-arylpropane-1, 2-diols in fairly good yields, as well as benzylic alcohols. It was revealed that benzaldehydes substituted with electron-withdrawing groups, which were previously reported to result only corresponding benzylic alcohols, were also reduced to give propanediol compounds in moderate yields. The reaction was shown to be highly diastereo-selective for erythro diols (>97% d.e.). The optical purities of the erythro isomers (1R, 2S) were also extremely high (>97% e.e.), and single recrystallization of dibenzoates gave optically pure diol derivatives within the limits of HPLC analysis.