Biocatalytic Conversion of Cyclic Ketones Bearing α‐Quaternary Stereocenters into Lactones in an Enantioselective Radical Approach to Medium‐Sized Carbocycles.

Abstract: Cyclic ketones bearing α‐quaternary stereocenters underwent efficient kinetic resolution using cyclohexanone monooxygenase (CHMO) from <italic>Acinetobacter calcoaceticus</italic>. Lactones possessing tetrasubstituted stereocenters were obtained with high enantioselectivity (up to >99 % <italic>ee</italic>) and complete chemoselectivity. Preparative‐scale biotransformations were exploited in conjunction with a SmI₂‐mediated cyclization process to access complex, enantiomerically enriched cycloheptan‐ and cycloctan‐1,4‐diols. In a parallel approach to structurally distinct products, enantiomerically enriched ketones from the resolution with an α‐quaternary stereocenter were used in a SmI₂‐mediated cyclization process to give cyclobutanol products (up to >99 % <italic>ee</italic>). [ABSTRACT FROM AUTHOR]