Abstract 9-(4'-Aminophenyl)-9H-pyrido [3, 4-b] indole 2 is a mutagenic compound produced by non-mutagenic norharman 1 and aniline in the presence of S9 mix. 9-(4'-Nitrophenyl)-9H- pyrido [3, 4-b] indole 4, the relay compound for synthesis of 2, was synthesized starting from ethyl indole-2-aldehyde 12 via initial N-(4-nitro) phenylation of the indole nucleus, elongation of the 2-aldehyde substituent, and then construction of the pyridine nucleus in ...