A highly efficient method for readily preparing 4,5-disubstituted 2H-1,2,3-triazoles was found. Under ambient conditions, a catalyst free cycloaddition between substituted vinyl sulfones and sodium azide could be completed in a very short time. In this cycloaddition process, sulfonyl group acts as a leaving group, while its ester group was retained. A highly efficient method for readily preparing 4,5-disubstituted 2H-1,2,3-triazoles was found. Under ambient conditions, a catalyst free cycloaddition between substituted vinyl sulfones and sodium azide could be completed in a very short time. In this cycloaddition process, sulfonyl group acts as a leaving group, while its ester group was retained. Copyright © 2012 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.