5-Amino-2-hydroxy-2,4,6-cycloheptatrien-1-one → 4-hydroxy-2-methyl-N-(2-hydroxy-1-oxo-2,4,6-cycloheptatrien-5-yl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide

Participants

Reaction Steps

In a nitrogen atmosphere, a solution of methyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide (0.54 g) and 5-amino-2-hydroxy-2,4,6 -cycloheptatrien-1-one (0.33 g) in xylene (15 ml) is refluxed for 7.5 hours. The reaction mixture is then allowed to stand at room temperature overnight. The crystals that have separated out are collected by filtration and recrystallized from dimethylformamidemethanol to give 4-hydroxy-2-methyl-N-(2-hydroxy-1-oxo-2,4,6-cycloheptatrien-5-yl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide (0.4 g), m.p. 258°-265° C.

Provenance & Evidence