Cu(I)-Catalyzed Asymmetric α-Allenylation of Activated Ketimines with 3-Butynoates

An asymmetric alpha-regioselective allenylation reaction of activated ketimines with 3-butynoates is disclosed under Cu(I) catalysis, probably via the generation of nucleophilic gamma-allenylcopper species in the presence of diisopropylethylamine. A broad range of imines, derived from diverse ketones such as isatins, pyrazolediones, isoquinoline-1,3,4-triones, and even trifluoromethyl alkynyl ketones, can be utilized, generally affording the corresponding alpha-allenyl amine derivatives in high yields (<= 97%) with excellent enantioselectivities (<= 99% ee).