Baker's yeast-mediated reduction of α-hydroxy ketones and derivatives: The steric course of the biotransformation

The results from the baker's yeast-mediated reduction of the acetates 3a-d and the methyl ethers 5a-d were compared with the same biotransformation which converts the alpha-hydroxy ketones 1a-d into the (R)-diols 2a-d (90-98%ee); the acetates 3a-d afford the (S)-monoacetates 4a-d (72-94% ee) and the methyl ethers 5a-d are reduced to the (R)-monoethers 6a-d (64-76% ee).