Synthesis, structure, and analgesic properties of halogen-substituted 4-hydroxy-2,2-dioxo-1H-2λ 6 , 1-benzothiazine-3-carboxanilides

Abstract

As potential new analgesics, the corresponding 4-hydroxy-2,2-dioxo-1H-2λ 6 ,1-benzothiazine- 3-carboxanilides have been obtained by amidation of ethyl 4-hydroxy-2,2-dioxo-1H-2λ 6 , 1-benzothiazine-3-carboxylate with aniline and its halogenated analogsin boiling dry xylene. The peculiarities of the mass and nuclear magnetic resonance (1H and 13C) spectra of the synthesized compounds are discussed. Using X-ray diffraction analysis, the ability of the compounds to form stable solvates with N,N-dimethylformamide has been shown on the example of 4-bromo-substituted derivative. It should be further studied to be considered in their crystallization. According to the results of the pharmacological testing conducted on the model of the thermal tail-flick (tail immersion test) among halogen-substituted 4-hydroxy-2,2-dioxo-1H-2λ 6 ,1-benzothiazine-3-carboxanilides, substances which are considerably superior to meloxicam and piroxicam by their analgesic activity have been found. They are of interest for further profound studies.