Rh-Catalyzed Reaction of Vinyl Azides with Isonitriles and Alkynes/Benzynes

In contrast to well-known transformations of vinyl azides via azirine intermediates or initiating at the alkene moiety, herein we report a Rh­(I)-catalyzed coupling reaction of vinyl azides with isonitriles at the azide moiety to form active vinyl carbodiimide intermediates and following tandem cyclization with unsaturated compounds, such as alkynes and benzynes, to give different classes of azaheterocycles. Mechanistically, controlled experiments and DFT calculations disclose that Rh-nitrene is the vital species in the first coupling step, and the Rh­(I) catalyst can also play an important role in the cyclization step of alkynes.