Synthesis of New 4-(dimethylamino)benzhydrazide Derivatives and Their Cyclization to 1,3-benzothiazin-4-one Moiety

The reaction of hydrazides of carboxylic acids with aldehydes is an efficient synthetic method to produce N-substituted hydrazone derivatives. The resulting hydrazone compounds are considered as convenient intermediates and can be used to obtain new interesting heterocyclic systems e.g. 1,3-thiazolidin-4-one or 1,3-benzothiazin-4-one derivatives. In the present work such pathway was used for the synthesis of new 1,3-benzothiazin-4-one derivatives (16-30). New compounds were obtained by the cyclization reaction of N-substituted 4-(dimethylamino)benzhydrazides (1-15) with thiosalicylic acid. The spectral (IR, 1H NMR, 13C NMR) and elemental analysis confirmed the structure of synthesized compounds.