Synthesis of Multisubstituted 1,2,3-Triazoles: Regioselective Formation and Reaction Mechanism

Abstract

A synthetically useful approach to functionalized triazoles is described via the reaction of β-carbonyl phosphonates and azides. 1,4-and 1,5disubstituted and 1,4,5-trisubstituted triazoles can be regio-and chemoselectively accessed under mild conditions in good to excellent yields (31 examples, up to 99%). A mechanism is proposed that rationalizes the avoidance of the 4phosphonate byproducts, which is aligned with crystallographic and experimental evidence.