Treatment of N-arylimino-1,2,3-dithiazoles 2 with ethylmagnesium bromi
de (2 equiv,) gives the corresponding aryl isothiocyanates 13, providi
ng a very mild two-step conversion of ArNH2 into ArNCS avoiding hazard
ous reagents; alternatively the iminodithiazoles 2 can be converted in
to cyanothioformanilides 11 which rapidly give the same isothiocyanate
s with 1 equiv, of the Grignard reagent.