Aqueous microwave assisted novel synthesis of isothiocyanates by amine catalysed thionation of isocyanides with Lawesson’s reagent Sodeeq Aderotimi Salami, Vincent J. Smith, Rui W.M. Krause Rhodes University, Grahamstown, South Africa A green and sustainable chemistry approach for organic synthesis is described here, which involves microwave exposure of reactants in the presence of water. A general, practical, and highly efficient protocol for the preparation of a broad range of functionalized isothiocyanates has been developed from their corresponding isocyanides using Lawesson’s reagent and catalytic amount of amine bases, particularly triethylamine under microwave irradiation conditions. As opposed to established approaches that employ toxic or volatile electrophilic liquids (thiophosgene, its derivatives, or CS 2 ) [1, 2]. In addition, these compounds were synthesized also by conventional heating procedures for comparison.A comparison between conventional and microwave-assisted synthesis was carried out by comparing total reaction time and percentage yield. The results suggest that microwave-assisted syntheses lead to higher yields within very short reaction times. References 1. Wong R, Dolman SJ. Isothiocyanates from tosyl chloride mediated decomposition of in situ generated dithiocarbamic acid salts,” J. Org. Chem. 2007;72;3969–3971, doi: 10.1021/jo070246n. 2. Bian G, Shan W, Su W.“A one-pot preparation of isothiocyanates from amines using two phosgene substitutes: bis-(trichloromethyl) carbonate and trichloromethyl chloroformates,” J. Chem. Res. , 2005; 9;585–586, doi: 10.3184/030823405774308862.
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