An efficient synthesis of 4,5-disubstituted-2H-1,2,3-triazoles from nitroallylic derivatives via a cycloaddition-denitration process

A metal-free convenient synthesis of 4,5-disubstituted N-unsubstituted 1,2,3-triazoles via a cycloaddition-denitration process has been described. A variety of readily available nitroallylic alcohols were reacted smoothly with sodium azide in the presence of p-toluenesulfonic acid (p-TsOH) to form synthetically viable triazolylacetates in good to high yields. Additionally, the nitroallylic acetates and sulfones were converted into structurally-modifiable triazolylazides and sulfone derived triazoles, respectively, in moderate to good yields. The present protocol is operationally simple, tolerates a broad range of functional groups and is also reliable in the case of a gram scale reaction under optimised reaction conditions. A practically-straightforward gram scale reaction for the synthesis of triazole directly from beta-nitrostyrene via a sequential one-pot Morita-Baylis-Hillman and cycloaddition reactions has been achieved.