The ligand-free copper-catalyzed hydroamination of allenes has been accomplished in the presence of cyclic secondary amines or anilines derivatives. This novel methodology undergoes the selective generation of (E)-allylamines under smooth conditions with total regio- and stereoselectivity.

A catalyst system composed of [(CMe)RuCl], potassium carbonate/guanidine carbonate, and mesitoic acid efficiently promotes the doubly regioselective C-H hydroarylation of unsymmetrical alkynes. The process involves carboxylate-directed ortho-C-H bond activation followed by regioselective addition to the alkyne C-C triple bond with concerted decarboxylation. This action of the carboxylate as a deciduous directing group ensures exclusive monovinylation with high selectivity for the (E)-1,2-diarylalkene.

Copper-catalyzed hydroamination of aromatic or heteroaromatic alkynes with cyclic secondary aliphatic amines undergoes generation of an enamine-type intermediate. The latter is transformed in situ via a coupling reaction with a second molecule of alkyne to afford regioselectively (1E,3E)-1,4-disubstituted-1,3-dienes with the formation of C-N, C-C, and C-H bonds.