A [3+2] cycloaddition-1,2-acyl migration-hydrolysis cascade for regioselective synthesis of 1,2,3-triazoles in water.

A cascade sequence involving [3+2] cycloaddition, 1,2-acyl migration and hydrolysis produces 2H-1,2,3-triazoles via the regioselective formation of N2-carboxyalkylated triazoles. The reaction proceeds in aqueous media through intriguing reaction kinetics using a CuI–prolinamide catalyst system. Prolinamide promotes the novel organocatalytic 1,2-acyl migration as well as hydrolysis of the resulting N2-carboxyalkylated triazoles.