On-Water Selectivity Switch in Microdroplets in the 1,2,3-Triazole Synthesis from Bromoethenesulfonyl Fluoride

J Am Chem Soc. 2021 Nov 10;143(44):18374-18379. doi: 10.1021/jacs.1c08879. Epub 2021 Oct 4.

Abstract

Water profoundly affects many organic reactions by accelerating them or changing their selectivity. Performing reactions "on-water" offers an intriguing opportunity to influence chemical reactivity. A nebulizer plume is an efficient way of generating microdroplets─the uniquely complex reaction environment which opens alternative possibilities that are not readily accessible in bulk emulsions. We describe the on-water switch of chemoselectivity in the formation of triazoles controlled by the on-water environment in dual spray. These conditions facilitate elimination of H-SO2F from the triazoline intermediate, whereas the reaction in organic solvents results in the exclusive HBr elimination. The influence of two-phase conditions was investigated to obtain the best reaction efficiency, and the crucial importance of the water/organic interface interactions was verified by pH variation and D2O use.