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Free keywords:
benzothiazinones; BTZ043; PBTZ169; nitrobenzoic acids; nitrobenzamides; antituberculosis drugs; hydrogen bonds; crystal structure
Abstract:
8-Nitro-1,3-benzothiazin-4-ones are a promising class of new antitubercular
agents, two candidates of which, namely BTZ043 and PBTZ169 (INN: macozinone), have reached clinical trials. The crystal and molecular structures of two synthetic precursors, 2-chloro-3-nitro-5-(trifluoromethyl)benzoic acid, C8H3ClF3NO4 (1), and 2-chloro-3-nitro-5-(trifluoromethyl)benzamide, C8H4ClF3N2O3 (2), are reported. In 1 and 2, the respective carboxy, carboxamide and the nitro groups are significantly twisted out of the plane of
the benzene ring. In 1, the nitro group is oriented almost perpendicular to the
benzene ring plane. In the crystal, 1 and 2 form O—H...O and N—H...O hydrogen-bonded dimers, respectively, which in 2 extend into primary amide tapes along the [101] direction. The trifluoromethyl group in 2 exhibits rotational disorder with an occupancy ratio of 0.876 (3):0.124 (3).