Versatile novel syntheses of imidazoles

A novel ring transformation/desulfurization of substituted 2-methyl-1,2,4-thiadiazolium salts 2 provides a versatile entry to imidazoles 3 with a variety of substituents. Simple one-pot procedures combine the preparation of starting 1,2,4-thiadiazolium salts 2 from N-(thiocarbonyl)-N'-methylamidines 1 or 1,2,4-dithiazolium triiodides 6 with the ring transformation/desulfurization to the imidazoles 3. Alternatively, N-(thiacarbonyl)-N'-methylamidines 1 can be transformed to imidazoles 3 or to 1-substituted imidazoles 5 via S-methylation and elimination of methylthiol. In the same manner, a new entry to 4H-imidazoles 8 could be developed.