Greener and Expeditious Synthesis of 1,4-Disubstituted 1,2,3-Triazoles from Terminal Acetylenes and in situ Generated α-Azido Ketones

A convenient and mild protocol for the one-pot regioselective synthesis of I,4-disubstituted 1,2,3-triazoles in aqueous PEG; 400 has been reported. The methodology involves the one-pot reaction of alpha-bromo ketones, sodium azide, and terminal acetylenes catalyzed by Cu(I) in aqueous PEG 400 at room temperature. Prominent features of our approach are mild reaction conditions, use of readily available alpha-bromo compounds, aqueous PEG 400 as a benign reaction medium, avoiding the isolation of labile alpha-azido ketones, simple workup, and good yields.