Eco-efficient, regioselective and rapid access to 4,5-disubstituted 1,2,3-thiadiazoles via [3 + 2] cycloaddition of α-enolicdithioesters with tosyl azide under solvent-free conditions
An operationally simple and facile synthesis of alpha-hydroxyimino-beta-oxodithioesters has been achieved by nitrosation of alpha-enolicdithioesters. They were further treated with internal alkynes to afford diverse 1,4-thiazin-3-ones via domino reduction/annulation strategy under mild reaction conditions. Importantly, this is the first straightforward entry to highly functionalized 1,4-thiazin-3-one derivatives from simple starting materials. (C) 2014 Elsevier Ltd. All rights reserved.