Copper Shines In Asymmetric Amine Synthesis

Molecule makers who want to construct amines adjacent to crowded carbons are getting a blue-light special. Here’s the deal: Chemists at Caltech led by Jonas C. Peters and Gregory C. Fu report they are able to make amines adjacent to fully substituted carbons via a reaction catalyzed by Earth-abundant copper that’s initiated with blue light (Science 2016, DOI: 10.1126/science.aad8313). Such amines are commonly found in natural products, pharmaceuticals, and agrochemicals. What’s more, the reaction is enantioselective, transforming a racemic mixture of a tertiary alkyl chloride into a single amine enantiomer. Peters and Fu believe the reaction proceeds via a radical mechanism. The researchers also point out that a single catalyst is responsible for both the photochemistry and the enantioselective bond formation. Most metal-catalyzed photoredox reactions reported to date use two separate catalysts to accomplish these tasks. “This work stands at a previously unexplored intersection of asymmetric synthesis, catalysis with Earth-abundant metals, photoinduced processes, and cross-coupling reactions of alkyl electrophiles, each of which represents an important current theme in chemical synthesis,” the chemists note.