A Metal-Free, Aqueous and General Route to 1,5-Disubstituted-1,2,3- triazoles: 'Reversed Regioisomeric' 1,3-Dipolar Cycloaddition of Azides and Vinyl Sulfones

A metal-free, vinyl sulfone-based synthesis of 1,5-disub- stituted-1,2,3-triazoles is reported for the first time. These triazoles are easily formed in a regioselective fashion by heating under reflux a mixture of a substituted vinyl sulfone and an organic azide 'on wa- ter'. This powerful and practical route has the potential to be ex- ploited for the synthesis of complex 1,5-disubstituted-1,2,3- triazoles.