Highly efficient and scalable chemoenzymatic syntheses of (R)- and (S)-lactaldehydes

Biocatalytic asymmetric reductions have been key steps in the synthesis of 1,1-dimethoxy-2-propanone, catalyzed by suitable ketoreductases to ( S )- and ( R )-1,1-dimethoxy-2-propanol, obtained in ≥99.9% ee and excellent yield. Removal of the protecting group gave the ( S )- and ( R )-lactaldehydes in excellent yield and purity.