3,1-BENZOXAZIN-4-ONES, 3,1-BENZOTHIAZIN-4-ONES AND N-ARYLCYANOTHIOFORMAMIDES

Anthranilic acid and 4,5-dichloro-1,2,3-dithiazolium chloride 1 give the delicate dithiazoloimino carboxylic acid 8 which on mild thermolysis gives 2-cyano-3,1-benzoxazin-4-one 6 and with triphenylphosphine gives 2-cyano-3,1-benzothiazin-4-one 7, both quantitatively; in general N-aryliminodithiazoles 2 with triphenylphosphine give the corresponding cyanothioformanilides 3, providing a route to these compounds from anilines in two mild steps.