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Short Paper | Regular issue | Vol 98, No. 1, 2019, pp.126-135
Published online, 18th January, 2019
DOI: 10.3987/COM-18-14021
■ Synthesis of 2H-Benzo[b]thietes by TFA-Mediated Cyclization of O-tert-Butyl S-(2-Vinylphenyl) Carbonothioates via 4H-3,1-Benzoxathiin-2-one Intermediates

Kazuhiro Kobayashi* and Takuma Ueyama

*Applied Chemistry Field, Chemistry and Biotechnology Course, Department of Engineering, Graduate School of Sustainability Science, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

An efficient method for the preparation of 2H-benzo[b]thiete derivatives under mild conditions has been developed. The reaction of 2-(1-arylethenyl)phenyl bromides with butyllithium at –78 ˚C generates 2-(1-arylethenyl)phenyllithiums, which are successively treated with sulfur and Boc2O at the same temperature to afford S-[2-(1-arylethenyl)phenyl] O-tert-butyl carbonothioates. These compounds are then treated with TFA at 0 or 20 ˚C to yield 2-aryl-2-methyl-2H-benzo[b]thietes via formation of the 4-aryl-4-methyl-4H-3,1-benzoxathiin-2-ones followed by decarboxylation.