Cobalt‐Catalyzed Enantioselective Hydrogenation of Trisubstituted Carbocyclic Olefins: An Access to Chiral Cyclic Amides

Abstract

AbstractThe enantioselective hydrogenation of cyclic enamides has been achieved using an earth‐abundant cobalt‐bisphosphine catalyst. Using CoCl2/(S,S)‐Ph‐BPE, several trisubstituted carbocyclic enamides were reduced with high activity and excellent enantioselectivity (up to 99 %) to the corresponding saturated amides. The methodology can be extended to the synthesis of chiral amines by base hydrolysis of the hydrogenation products. Preliminary mechanistic investigations reveal the presence of a high spin cobalt (II) species in the catalytic cycle. We propose that the hydrogenation of the carbon‐carbon double bond proceeds via a sigma‐bond‐metathesis pathway.