The chemistry of 2,1-benzisothiazoles. Part VII. Reaction of α-substituted o-toluidines with thionyl chloride. A one-stage synthesis of 2,1-benzisothiazole-3-carboxylic acid
- 1 January 1973
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- p. 2057-2059
- https://doi.org/10.1039/p19730002057
Abstract
o-Benzylaniline (II; R = Ph) affords a quantitative yield of 3-phenyl-2,1-benzisothiazole (III; R = Ph) when heated with thionyl chloride, but o-toluidines functionally substituted at the methyl group (II; R = CN, OH, or Cl) give only N-sulphinyl derivatives or tars. o-Ethylaniline (II; R = Me) probably affords 3-methyl-2,1-benziso-thiazole (III; R = Me) as an intermediate, but the latter is rapidly chlorinated at the methyl group, and after hydrolysis 2,1-benzisothiazole-3-carboxylic acid (III; R = CO2H) is obtained in 30% yield. More highly substituted o-alkylanilines produce N-sulphinylamines, only traces of 2,1-benzisothiazoles being formed.Keywords
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