Asymmetric Propargylic Radical Cyanation Enabled by Dual Organophotoredox and Copper Catalysis

The
first asymmetric propargylic radical cyanation was realized
through a dual photoredox and copper catalysis. An organic photocatalyst
serves to both generate propargyl radicals and oxidize Cu­(I) species
to Cu­(II) species. A chiral Cu complex functions as an efficient organometallic
catalyst to resemble the propargyl radical and cyanide in an enantio-controlled
manner. Thus, a diverse range of optically active propargyl cyanides
were produced with high reaction efficiency and enantioselectivities
(28 examples, 57–97% yields and 83–98% ee). Moreover,
mechanistic investigations including experiments and density functional
theory calculations were performed to illustrate on the reaction pathway
and stereochemical results.