Decarboxylative cyanation and thiocyanation via catalytic electron donor-acceptor complex with copper catalysis

A new catalytic decarboxylative cyanation and thiocyanation via a synergistic NaI/Cu catalysis is developed. The photoexcited electron donor-acceptor complex by assembly of NaI, R₃P, and N-acyloxy-phthalimide ester (NHPI ester) triggers the generation of alkyl radical species, which then engages in Cu-catalyzed radical coupling process. Key to success of this dual catalytic transformation is the reliable charge transfer between I· and Cu(I). This dual catalytic platform can eliminate the use of expensive iridium-based photocatalyst or synthetically elaborate organic dyes. A series of primary, secondary, and tertiary alkyl nitriles and thiocyanates are easily synthesized. Moreover, an asymmetric decarboxylative cyanation by applying a chiral Cu catalyst is also developed to afford chiral nitriles in high enantioselectivity. The mechanistic details and the origin of the high enantioselectivity are further investigated by the mechanistic experiments and the density functional theory calculations.