Nickel-Catalyzed Defluorinative Coupling of Aliphatic Aldehydes with Trifluoromethyl Alkenes.

A simple procedure is reported for the nickel-catalyzed defluorinative alkylation of unactivated aliphatic aldehydes. The process involves the catalytic reductive union of trifluoromethyl alkenes with aldehydes using a nickel complex of a 6,6'-disubstituted bipyridine ligand with zinc metal as the terminal reductant. The protocol is distinguished by its broad substrate scope, mild conditions, and simple catalytic setup. Reaction outcomes are consistent with the intermediacy of an α-silyloxy(alkyl)nickel intermediate generated by a low-valent nickel catalyst, silyl electrophile, and the aldehyde substrate. Mechanistic findings with cyclopropanecarboxaldehyde provide insights into nature of the reactive intermediates and illustrate fundamental reactivity differences that are governed by subtle changes in ligand and substrate structure.