SYNTHESIS OF NEW N-AROYLISOTHIAZOLE-2-IMINES AND N-AROYLAMINOISOTHIAZOLIUM SALTS BY CYCLIZATION OF THIOCYANATO-SUBSTITUTED HYDRAZONES

The synthesis of new N-aroylisothiazole-2-imines (4g-n) as well as the corresponding acceptor-substituted 2-amino-isothiazolium salts (6f-n) by cyclocondensation of thiocyanatovinylaldehyde hydrazones (3) is reported. The structure of these N-imines was proved by spectroscopic methods. The alternative cyclization route to 1,2,3-thiadiazines (8) is not observed. The hydrazones (3a-e) could not be cyclized to N-imines, only sulfides (5a-c) were obtained. The reaction of 2-thiocyanatomethylen-cycloheptan-2-one (9) with benzhydrazides gave the same ring closure to the salts (10a,b). The structure of the N-imine 11b has been confirmed unequivocally by X-ray structure analysis.