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Short Paper | Special issue | Vol 99, No. 1, 2019, pp.583-595
Published online, 20th April, 2018
DOI: 10.3987/COM-18-S(F)1
A Convenient Synthesis of 2-(Alkyl(or Aryl)sulfanyl)-2H-1,4-benzothiazin-3(4H)-one Derivatives

Kazuhiro Kobayashi,* Kazuki Kawano, and Keita Yamashita

*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

A convenient method for the preparation of 2-(alkyl(or aryl)sulfanyl)-2H-1,4-benzothiazin-3(4H)-one derivatives has been developed. Thus, methyl alkyl(2-{[(alkyl(or aryl)sulfanyl)methyl]sulfanyl}phenyl)carbamates, derived from commercially available 2-aminobenzenethiol by an easily operated three-step sequence, are treated with two equivalents of lithium diisopropylamide (LDA) to generate carbanions stabilized by the adjacent two sulfur atoms, which immediately undergo 2H-1,4-benzothiazin-3(4H)-one ring formation by intramolecular attack onto the carbamate carbonyl accompanying elimination of methoxide. In addition, direct or stepwise introductions of alkyl groups to the 2-position are reported.