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Modular Synthesis of N‑Vinyl Benzotriazoles

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journal contribution
posted on 2013-08-16, 00:00 authored by Govindra Singh, Rakesh Kumar, Jorge Swett, Barbara Zajc
A modular approach to N1-vinyl benzotriazoles by azide–aryne cycloadditions and Julia–Kocienski reactions is described. Reactions of azidomethyl phenyl-1H-tetrazol-5-yl (PT) sulfide with arynes gave methyl(PT-sulfanyl)-substituted benzotriazoles in 68–89% yields. Oxidation of the sulfides to the sulfones gave the benzotriazole-substituted Julia–Kocienski reagents. Olefination reactions of aldehydes and a ketone with reagents derived from benzyne, 2,3-naphthyne, and 4,5-dimethoxybenzyne precursors proceeded to give various N1-vinyl benzotriazole derivatives. Olefination stereoselectivities are tunable for electron-rich aldehydes, but not for electron-deficient aldehydes and alkanals, where they proceed with good to excellent Z-stereoselectivity.