Cu(I)-azidopyrrolo[3,2‑d]pyrimidine Catalyzed Glaser–Hay Reaction under Mild Conditions

The limitation of the CuAAC “click” reaction with a 2-azidopyridine substrate, owing to its equilibrium with a tetrazole isomer, is exploited herein for its utility in the Glaser–Hay reaction. A catalytic combination of a 2-azidopyridine analogue, 4-azido-5H-pyrrolo­[3,2-d]­pyrimidine, and CuI afforded homocoupled products of terminal alkynes, without any trace of triazole product, under mild conditions with a broad substrate scope. Emphasis on carbohydrate-based substrates appended to a propargylic group led to 1,3-diynes in good to excellent yields.