Synthesis of pyridocarbazoles for anti-tumour studies

Abstract

Cyclodehydration in orthophosphoric acid of the azomethines of 3- formyl-carbazoles and aminoacetals has yielded 5-methyl- (IId), 3,5,11- trimethyl-(11b), 3,5,9,11-tetramethyl-(IIc), and 5,7,10,11-tetramethyl- 6H-pyrido[4,3-b]carbazoles (IIa). In the same way γ-carboline and 6,9- dimethyl-γ-carboline were obtained from the azomethines of 3-formyl- and 3-formyl-4,7-dimethyl-indole. A Doebner reaction with 3-amino-2- methylcarbazole, acetaldehyde, and pyruvic acid yielded 1-carboxy-3,5- dimethyl-7H-pyrido[2,3-c]carbazole (VIIIb) from which was derived the methyl ester (VIIIc) and 3,5-dimethyl-7H-pyrido [2,3-c]carbazole (VIIIa).