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Abstract

1,3-Benzothiazin-4-ones (BTZs) are a promising new class of anti-tuberculosis
drug candidates, some of which have reached clinical trials. The title compound,
the benzamide derivative [2-chloro-3-nitro-5-(trifluoromethyl)phenyl](piperidin-1-yl)methanone, C₁₃H₁₂ClF₃N₂O₃, occurs as a side product as a result of
competitive reaction pathways in the nucleophilic attack during the synthesis of
the BTZ 8-nitro-2-(piperidin-1-yl)-6-(trifluoromethyl)-1,3-benzothiazin-4-one,
following the original synthetic route, whereby the corresponding benzoyl
isothiocyanate is reacted with piperidine as secondary amine. In the title
compound, the nitro group and the nearly planar amide group are significantly
twisted out of the plane of the benzene ring. The piperidine ring adopts a chair
conformation. The trifluoromethyl group exhibits slight rotational disorder with
a refined ratio of occupancies of 0.972 (2):0.028 (2). There is structural evidence
for intermolecular weak C—H...O hydrogen bonds.