By Oxidation of a-Arylhydrazono-thioamides

By Oxidation of a-Arylhydrazono-thioamides. The a-arylhydrazono-thioamides (10), prepared by the action of hydrogen sulphide on arylhydrazonocyanoacetic acid derivatives ArNHN=CRCN, undergo oxidative cyclization to 5-amino-2-aryl-l,2,3-thiadiazolium salts (11) (65—90%). On acetylation, they give 5-acetyl-imino-2-aryl-4-carboxylic acid derivatives (12).  

The action of alkalis on (11) regenerates the starting materials (10). Treatment with acetoacetic ester produces, by S—N bond fission and recyclization, good 

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