Synthesis of novel 2‐aminoimidazo[4,5‐<i>b</i>]pyridines, including the thieno analogue of the cooked‐food mutagen IFP

Abstract

Abstract magnified image Eight new compounds, including three new ring systems obtained via the Friedländer condensation of ortho ‐aminothiophenecarbaldehydes 11, 21 and 24 with creatinine (8), are reported. The condensation afforded 1, which is the thieno analogue of the cooked‐food mutagen IFP (2‐amino‐1,6‐dimethylfuro[2,3‐ e ]imidazo[4,5‐ b ]pyridine), and the benzothieno[2,3‐ e ]‐ and benzothieno[3,2‐ e ]imidazo[4,5‐ b ]pyridines 2 and 3. Attempts to condense 11 with isocreatinine (12) were unsuccesful. Desulfurization of 3 gave the known cooked‐food carcinogen PhIP. The 2‐nitro (4) and 2‐hydroxy (5) derivatives of 3 are reported. The related 2‐amino‐1‐methyl‐imidazo[4,5‐ b ]benzothiophene (25) was synthesized by a different route. Fully assigned 1 H and 13 C nmr data of all new compounds are reported.