Enantioselective Copper‐Catalyzed Radical Ring‐Opening Cyanation of Cyclopropanols and Cyclopropanone Acetals

A novel approach for enantioselective cyanation of cyclopropanols and their derivatives through copper‐catalyzed radical relay processes has been developed. Various cyclopropanols and cyclopropanone acetals are compatible to the catalytic conditions, providing β‐carbonyl nitriles with excellent enantioselectivity. These products can be readily converted to chiral γ‐amino acids derivatives and drugs such as (R)‐baclofen. Preliminary mechanistic studies have supported a ring‐opening process for cyclopropanoxy radicals followed by copper‐catalyzed enantioselective cyanation of benzylic radicals to form the C−CN bonds in an enantioselective manner.