The Synthesis of Pyridocarbazoles

7H-Pyrido(2,3-c)- (IX, R=H) and 7H-pyrido(3,2-c)carbazole (V, R=H) have been synthesized by unambiguous routes and shown to be identical with the products resulting from the Fischer-indole ring closure followed by dehydro-genation of 6- and 7-quinolylhydrazone of cyclohexanone respectively. The cyclization of N-substituted-1,2,3,4-tetrahydro-6- and -7-quinolylhydrazone of cyclohexanone followed by hydrolysis and dehydrogenation resulted in the linear polycyclic systems, 6H-pyrido(3,2-b)- (VIII) and 10H-pyrido(2,3-b)carbazole (IV) respectively. The 12 possible pyridocarbazoles have now been prepared.The structure of the Skraup reaction product of 1-phenyl-5-amino-1-benzo-triazole (X) has been established.