Catalytic Metallonitrene/Alkyne Metathesis: A Powerful Cascade Process for the Synthesis of Nitrogen-Containing Molecules

A conceptually novel metallonitrene/alkyne metathesis cascade reaction has been developed for the construction of nitrogen-containing compounds from simple alkyne starting materials. Rhodium(II) tetracarboxylate salts are efficient catalysts for this reaction, in which an electrophilic rhodium nitrene is trapped by an alkyne, resulting in the formation of a new C-N bond and the generation of a reactive metallocarbene for cascade reaction. The reaction is tolerant of both alkyl and aryl substituents on the alkyne, and proceeds at room temperature in a variety of common solvents. The modular nature of the reaction allows for the rapid construction of congested bicyclic systems from remarkably simple alkyne starting materials.