Preparation of New Chiral Building Blocks: Highly Enantioselective Reduction of Prochiral 1,3-Cycloalkanediones Possessing a Methyl Group and a Protected Hydroxymethyl Group at Their C2 Position with Baker's Yeast or CBS Catalyst

Highly enantioselective reduction of five-, six-, seven-, and eight-membered prochiral 1,3-cycloalkanediones possessing a methyl group and a protected hydroxymethyl group at their C2 position with baker's yeast or CBS catalyst and a new efficient and general method for preparing the 1,3-cycloalkanediones have been developed. These baker's yeast mediated reductions were found to produce corresponding ketols with high optical purity (>99% ee) and high yield. All of the prepared ketols and their derivatives, chiral building blocks, have been fully characterized, and their absolute configurations have been determined. These compounds would be useful for the convergent synthesis of complex natural products.