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

Abstract

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).

N‐Arylcyanothioformamides: Preparation Methods and Application in the Synthesis of Bioactive Molecules

“…As such, imidazole‐4‐thiols such as those belonging to the ovothiols family of antioxidants have become attractive synthetic targets . Building on the reported heterocyclic ring‐closure reactions of N ‐arylcyanothioformamides with electrophilic reagents, it was envisaged that using N ‐substituted aldimines as the electrophilic species should provide access to imidazoline‐4‐thiones which may serve as possible precursors of ovothiols . The presence of a 5‐amino group in the target product counts as an additional feature which may assist in scavenging free‐radicals.…”