Rhodium-Catalyzed Transannulation of 4,5-Fused 1‑Sulfonyl-1,2,3-triazoles with Nitriles. The Selective Formation of 1‑Sulfonyl-4,5-fused Imidazoles versus Secondary C–H Bond Migration

The reactivity of readily available 4,5-fused-1-sulfonyl-1,2,3-triazoles was examined in the Rh­(II)-catalyzed transannulation reaction with nitriles. We have come across the interesting observation that 1-sulfonyl cycloalkeno­[d]­[1,2,3]­triazoles that possess β-hydrogens resist intramolecular β-hydride migration and could serve as a new source of Rh-iminocarbenoids for intermolecular Rh­(II)-catalyzed transannulation reactions. As a result, 1-sulfonyl cyclohexeno-, cyclohepteno-, dihydropyrano-, 5-phenyltetrahydrobenzo-, and 4,5-dihydronaphtho­[d]­imidazoles were synthesized from various nitriles in good yields. A one-pot methodology has also been executed for the synthesis of NH-imidazoles.