Cobalt-Catalyzed Enantioselective Intermolecular C–H Carboamination with Racemic Allenes

Abstract

Enantioselective carboamination of allenes especially in conjunction with 3D-metal catalysis remains a significant challenge. We report chiral cyclopentadienyl cobaltIII-catalyzed regio-, chemo-, and enantioselective intermolecular C–H carboamination of racemic allenyl esters with N-phenoxyisobutyramides. The protocol offers an efficient approach for highly selective carboamination of allenes and affords synthetically valuable chiral γ-substituted-β-enamido esters with exceptional selectivities (up to 88% yield, >99:1 er, and >20:1 E/Z). Operating by a kinetic resolution pathway, the transformation was additionally optimized for recovery of enantioenriched allenes with high selectivity factors of up to 138. The utility was showcased by the resolution of methyl-(R,E)-(−)-tetradeca-2,4,5-trienoate, the male bean weevil pheromone.