Imidazoline‐4‐thiones from cyanothioformamides and aldehyde imines: Formation, aromatization, and acetylation

The reaction of N ‐methyl‐ ( 3a ) or N ‐phenylcyanothioformamide ( 3b ) with acetaldimine ( 5a , as 1‐amino‐1‐ethanol) gives 5‐(amino)imidazolidine‐4‐thiones 6B . Product 6a reacts with a second equivalent of 3a to give 8 which in turn is oxidized to disulfide 9 . Using araldimines 5b , 5c , only 1:2 intermediates 10 derived from 3a , 3b and two moles of the imine 5 are formed, but proved to be easily oxidized to disulfides 11 . Acetylation of 6 occurs chemoselectively on the exocyclic nitrogen and finally also on the thione sulfur to give 14 via 13 . J. Heterocyclic Chem., (2010).