Regioselectivity of aryl azide cycloaddition to methyl propiolate in aqueous media: experimental evidence versus local DFT HSAB principle

The regioselectivity of the 1,3-dipolar cycloaddition of a series of 4-substituted-phenyl azides to methyl propiolate in aqueous medium has been determined experimentally. Ab initio B3LYP/6-311+G(d, p) calculations in conjunction with the local HSAB principle developed within density functional theory provided a full rationalization of cycloaddition regioselectivity