New syntheses of aryl isothiocyanates from N-arylimino-1,2,3-dithiazoles

Treatment of N-arylimino-1,2,3-dithiazoles 2 with ethylmagnesium bromide (2 equiv,) gives the corresponding aryl isothiocyanates 13, providing a very mild two-step conversion of ArNH2 into ArNCS avoiding hazardous reagents; alternatively the iminodithiazoles 2 can be converted into cyanothioformanilides 11 which rapidly give the same isothiocyanates with 1 equiv, of the Grignard reagent.