- Ring contraction of 3-carboxamide or 3-carboxylate of 4-hydroxy-2- methyl-2H-1,2-benzothiazine-1,1-dioxide and analogous 1 (2H)-isoquinolinone- 3-carboxylate
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A novel ring transformation of 3-carboxylate or 3-carboxamide of 4- hydroxy-2-methyl-2H-1,2-benzothiazine-1,1-dioxide and analogous 1(2H)- isoquinolinone-3-carboxylate to the 5-membered rings upon the reaction with carbonyl compounds in the presence of primary or secondary amines is described.
- Khalaj, Ali,Adibpour, Neda
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p. 131 - 135
(2007/10/03)
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- TITANIUM-MEDIATED DIECKMANN CONDENSATION
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The Dieckmann condensation of alkyl 2-(N-methyl-N-(alkoxycarbonylmethyl)sulfamoyl)-benzoates Ia and Ib with titanium tetrachloride-tert-amine or butyltitanium ate complex III affords alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides IIa and IIb which are the piroxicam intermediates.
- Patek, Marcel
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p. 1223 - 1227
(2007/10/02)
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- Process for obtaining 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide
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A process for obtaining 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide, which may be used as a non-steroidal analgesic and anti-inflammatory drug. The process comprises reacting saccharin sodium with isopropyl chloroacetate in dimethylformamide, reacting the resultant isopropyl 3-oxo-1,2-benzoisothiazoline-2-acetate 1,1-dioxide with sodium isopropylate in isopropanol to produce an intermediate which, when methylated in an aqueous-alcoholic basic medium with dimethyl sulfate, gives an intermediate compound which when condensed with 2-aminopyridine in xylene, yields 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazone-3-carboxamide 1,1-dioxide.
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- CONDITIONS OF THE DIECKMANN CONDENSATION OF ALKYL 2-(N-METHYL-N-(ALKOXYCARBONYLMETHYL)SULFAMOYL-BENZOATES
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The Dieckmann condensation of alkyl 2-(N-methyl-N-(alkoxycarbonylmethyl)sulfamoyl)benzoates IIIa-IIIe with various bases affords alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides IVa-IVe which are intermediates in the synthesis of antiinflammatory drug piroxicam.The yields of benzothiazines IVa-IVe depend mostly on the nature of a base, reaction temperature and solvent used for these condensations.Hitherto undescribed esters IIIb-IIIe were sythesized and their structures were confirmed by 1H and 13C NMR, and mass spectra.
- Patek, Marcel,Hampl, Frantisek
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p. 3267 - 3277
(2007/10/02)
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