Nitric Acid → 5,7-Difluoro-3,4-dihydro-3-oxo-2H-1,4-benzothiazine-6-carboxylic acid

Participants

Reaction Steps

Ethyl 3-nitro-2,4,6-trifluorobenzoate. To a suspension of ethyl 2,4,6-trifluorobenzoate (3.93 g, 19.2 mmol) in conc. H2SO4 at 0° C. was added conc. HNO3 (70% HNO3) dropwise via pipet. After the addition was complete, the reaction was allowed to warm to RT and stir for 4 h. The biphasic mixture was poured into H2O and extracted with CH2Cl2 (3×). The combined organic layers were dried (Na2SO4) and concentrated to provide 4.71 g (98%) of the title compound as a yellow solid. 1H NMR (400 MHz, CDCl3): 6.96 (ddd, J=9.2, 9.2, 2.2, 1H), 4.45 (q, J=7.2, 2H), 1.40 (t, J=7.2, 3H).

Provenance & Evidence