Cu(I)-Catalyzed Three-Component Reaction of α-Diazo Amide with Terminal Alkyne and Isatin Ketimine via Electrophilic Trapping of Active Alkynoate-Copper Intermediate.

A three-component reaction between terminal alkyne, α-diazo amide, and isatin ketimine is realized by utilizing copper catalysis. A series of alkynyl-containing 3,3-disubstituted oxindoles were synthesized with high efficiency and diastereoselectivity under mild reaction conditions. This transformation is proposed to proceed through a Mannich-type trapping of an alkynoate copper intermediate derived from terminal alkyne and copper carbene species.