Formaldehyde → 7-chloro-4-(4-chlorophenyl)-2-(hydroxymethyl)-5H-pyrido[3,4-b][1,4]benzothiazin-3(2H)-one

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Reaction Steps

To 5.0 g. of 7-chloro-4-(4-chlorophenyl)-5H-pyrido[3,4-b][1,4]-benzothiazin-3(2H)-one (13.8 mmol.) in 50 ml. dimethylformamide was added 30 ml. of a 5% sodium hydroxide solution (37.5 mmol.) and the resulting suspension was heated on a steam bath until the solid dissolved. To the resulting solution was then added 50 ml. of 36% formaldehyde solution (60.0 mmol.), and the resulting reaction mixture was heated on a steam bath for 30 minutes, then cooled to room temmperature, yielding a yellow precipitate. The mixture was filtered, and the collected precipitate was washed with water and dried under vacuum at room temperature to yield 7-chloro-4-(4-chlorophenyl)-2-(hydroxymethyl)-5H-pyrido[3,4-b][1,4]benzothiazin-3(2H)-one as a yellow solid (4.7 g.; 87% yield) having the structural formula, ##STR13## a melting point of 295°-300° C. (with decomposition) and the following elemental analysis:

Provenance & Evidence