A CONVENIENT SYNTHESIS OF 2-(ALKYL(OR ARYL)SULFANYL)-2H-1,4-BENZOTHIAZIN-3(4H)-ONE DERIVATIVES

摘要

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.