Photoinduced, copper-catalyzed coupling reaction

Abstract

The Ullmann reaction to form C- N bonds, first described over a century ago, is now a classic method in org. synthesis. During the time since its discovery, there had been no reports of a photoinduced variant. Instead, copper- mediated and coppercatalyzed processes have generally been effected with the aid of heat (e.g., at 60- 120 ° C) . Recently, we have established that a photoinduced Ullmann C- N arylation can proceed at a temp. as low as - 40 ° C. The reaction of an amine with an alkyl halide is a classic "textbook" approach to C- N bond construction. For efficient C- N bond formation, the electrophile should generally be a good substrate for an S_N2 reaction. A mild, transition metal- catalyzed N- alkylation that proceeds through a radical pathway for C- X cleavage has the potential to address important limitations of the classic S_N2 approach. In this lecture, recent efforts to address this challenge will be described.