Divergent Synthesis of CF3 -Substituted Allenyl Nitriles by Ligand-Controlled Radical 1,2- and 1,4-Addition to 1,3-Enynes.

A ligand-controlled system that enables regioselective trifluoromethylcyanation of 1,3-enynes has been identified, which provides access to a variety of CF3 -containing tri- and tetrasubstituted allenyl nitriles. We disclose that the involved propargylic radicals can be selectively trapped by (Box)CuII cyanide, while the tautomerized allenyl radicals are trapped by (phen)CuII cyanide (Box= bisoxazoline, phen=phenanthroline). In addition, the reaction features broad substrate scope and excellent functional group compatibility. Moreover, this protocol represents a novel regioselectivity-tunable functionalization of 1,3-enynes via radicals, which we believe will have great implications for the development of catalytic systems for selectivity control in radical and organometallic chemistry.