Dual Photoredox and Copper Catalysis: Enantioselective 1,2-Amidocyanation of 1,3-Dienes

Dual photoredox–transition-metal
catalysis has emerged as
a powerful tool for the development of chemical transformations. However,
its application in the selective difunctionalization of 1,3-dienes
remains essentially unexploited. By the synergistic action of photoredox
and copper catalysts, we report herein an enantioselective 1,2-amidocyanation
of 1,3-dienes. Visible-light irradiation of a chloroform solution
of conjugated dienes, N-Boc-amidopyridinium salts,
and TMSCN in the presence of a catalytic amount of fac-Ir(ppy)3, Cu(OTf)2·xH2O, and a chiral Box ligand affords three-component adducts
in good to high yields with high regio- and enantioselectivities.
A L*CuCN complex, fully characterized spectroscopically and confirmed
by X-ray crystallographic analysis, is able to catalyze the transformation,
therefore supporting an inner-sphere cyanide transfer pathway.