Baker's yeast mediated reduction of dihydroxyacetone derivatives

Several monoprotected dihydroxyacetone derivatives 4a–d and their acetates 5a–d were prepared and subjected to biotransformation with baker's yeast. The simple chemical modification of the substrates (i.e. transforming the relatively small hydrophilic hydroxymethyl group into a larger hydrophobic acetoxymethyl moiety) inverted the sense of enantiotope selectivity of these reductions yielding optically active diols 6a–d, or their enantiomeric acetates (7a–d) and diols (ent-6a–d), respectively.