Reactivity of N-(1,2,4-triazolyl)-substituted 1,2,3-triazoles

Synthetically useful rhodium(II) carbenes were obtained from N-(1,2,4-triazolyl)-substituted 1,2,3-triazoles and Rh(II) carboxylates. The electron-withdrawing 1,2,4-triazolyl group reveals the heretofore unknown reactivity of nonsulfonyl 1,2,3-triazoles, which exhibit the reactivity of diazo compounds. The resulting carbenes provide ready asymmetric access to secondary homoaminocyclopropanes (80-95% ee, dr >20:1) via reactions with olefins and also engage in efficient transannulation reactions with nitriles.