An Easy Photochemical Approach to the Synthesis of the Food‐Borne Carcinogen 2‐Amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine.

Abstract Mutations induced by substances formed during food cooking are a field of growing interest; for a better comprehension of the mechanism of action of these carcinogens, simple routes to their synthesis are needed. In this letter we describe an easy method for 2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine (PhIP) synthesis, starting from the commercially available 2,3-diaminopyridine 1 via the 2-amino-3-methylamino-5-phenylpyridine 5 formation. The key step of this approach is the one pot synthesis of 5 performed by photolysis of 2-amino-5-iodo-3-( N -methyl- N -tosylamino)pyridine 4 to obtain simultaneous phenylation and tosyl group removal. Compound 5 was then used as an intermediate to obtain the 1-methyl-6-phenylimidazo[4,5- b ]pyridine 6 which was aminated to afford PhIP in good overall yields.