Asymmetric synthesis of O-protected acyloins using enoate reductases: Stereochemical control through protecting group modification

摘要

O-Protected cyclic acyloins were obtained in nonracemic form through asymmetric bioreduction of α,β-unsaturated alkoxy ketones by using 11 different enoate reductases from the "Old Yellow Enzyme" family. The stereochemical outcome of the biotransformation could be switched by variation of the O-protecting group or by the ring size of the substrate, which allows access to both stereoisomers in up to >97 % ee Whereas α-alkoxy enones were readily accepted as substrates, β-analogs were not converted. Overall, α-alkoxy enones represent a novel type of substrate for flavin-dependent ene-reductases.