Enantioselective C(sp3)−H Dienylation of Thioamides Under Cp*Co(III)/Chiral Acid Catalysis

A catalytic enantioselective β-C(sp³)–H dienylation of thioamides has been developed using a cationic Cp*Co(III) complex in combination with a chiral binaphthyl-derived carboxylic acid. Allenyl carbonates serve as efficient diene surrogates, enabling regio-, and enantioselective C–H functionalization under mild conditions. The reaction exhibits broad functional group tolerance, affording synthetically valuable dienylated products in high yields and up to 95:5 enantiomeric ratios. Mechanistic experiments supported by DFT calculations, identify C–H activation as the enantio-determining step, migratory insertion as the rate-limiting step with the steric and electronic properties of the chiral acid being crucial for asymmetric induction.