Rapid synthesis of 2-cyanobenzothiazole, isothiocyanate and cyanoformanilide derivatives of dapsone

New derivatives of the leprostatic drug dapsone are prepared by way of imin o-1,2,3-dithiazoles obtained by condensation of aromatic primary bisamines, including dapsone, with 4,5-dichloro-1,2,3-dithiazolium chloride (Appel sa lt). Reactions, including microwave irradiation, initiated by nucleophilic attack at different sites of the dithiazole ring transform the bisiminodith iazoles into the symmetrical, and some unsymmetrical, title compounds.