Mutagenic heterocyclic nitrogen compounds related to protein pyrolysates. 1 . Derivatives of dipyrido[1,2‐ a :3′,2′‐ d ]imidazole

2‐Amino‐6‐methyldipyrido[1,2‐ a :3′‐2′‐ d ]imidazole is one of the mutagenic principles of L‐glutamic acid and casein pyrolysates. We prepared several isomeric amines of this compound, as well as their homologues methylated in different positions on the heterocyclic ring, either by nitration of the ring followed by reduction or from appropriate 4‐azidodipyrido[1,2‐ a :3′,2′‐ d ]imidazoles. The latter compounds, the heterocyclic ring itself and various functional derivatives (hydroxylated, carboxylated, hydrazinic) were synthesized from 2‐aminoimidazo[1,2‐ a ]pyridines via various reactions which are described herein.