Synthesis of novel 8-nitro-substituted 1,3-benzothiazin-4-ones

Synthetic approaches to 2-aryl/hetaryl- and 2-(hetaryl)ylidene derivatives of fluorinated 1,3-benzothiazin-4-ones

“…The signals of Н 6 and Н 7 in 1 H NMR spectra of benzothiazinones 5-9 exhibit more complicated multiplicity than in the case of 2,5-diaminobenzothiazinones [8], which indicates that the fluorine atom remains in position 5. To prove that the alternative product of cyclization, 5-fluoro-6-nitro isomer, was not formed 19 F NMR spectra without suppression of F-H spin-spin interaction were registered.…”

“…3-Nitro-2,6-difluorobenzoic acid 2 was synthesized according to the literature [9]. Procedure for toluene solution of 2,6-difluoro-3-nitrobenzoylchloride 3 was reported [8]. 2-Benzoylmethylbenzimidazole was prepared from 2-methylbenzimidazole [5], 2-cyanomethyl-benzimidazole was synthesized by condensation of ethyl cyanoacetate with o-phenylenediamine [10].…”

“…Previously we studied the interaction of polyfluorobenzoylisothiocyanates with CH-reactive benzimidazoles [5], 2,6-difluorobenzoylisothiocyanate with the same benzimidazoles and 2-cyanomethylpyridine [6], o-fluorobenzoylisothiocyanates with N-methylpyrrole and N-methylindole [7]. We presented only one example of 2-indolyl-5-fluoro-8-nitro-1,3-benzothiazin-4-one in recent paper [8].…”