Copper-Catalyzed One-Step Formation of Four C-N Bonds toward Polyfunctionalized Triazoles via Multicomponent Reaction.

A novel four-component reaction of alkynes, amines, azides, and 2H -azirines has been developed for the first time by the efficient formation of four C-N bonds in one step under mild conditions, rapidly preparing polyfunctionalized triazoles with molecular diversity involving three different intermediates of copper-acetylide, copper-allenylidene, and copper-vinyl nitrene. Propargylic ester is disclosed as a "three-in-one" building block possessing triplicate cycloaddition and nucleophilic and electrophilic properties, which could enable such a four-component transformation by high yields, broad substrate scope, and functionalization.