Nickel Photocatalyzed Reductive 1,4-Dicarbofunctionalization of 1,3-Enynes with N -Methylamines and Organohalides Enabled by Site-Selective C(sp 3 )-H Functionalization.

A cooperative nickel and photoredox reductive catalysis for 1,4-dicarbofunctionalization of 1,3-enynes with tertiary N -methylamines and organohalides to produce tetrasubstituted allenes is presented. This method enables the generation of the aminoalkyl C(sp 3 )-centered radicals by site selective cleavage of the N -methyl C(sp 3 )-H bonds in tertiary N -methylamines and is extended to alkyl bromides as the electrophilic terminating regents. Mechanistic studies indicate that the reaction involves a radical process and a Ni 0 /Ni I /Ni III catalytic cycle.