Synthesis and reactions of 4‐hydroxy‐8,9,10,11‐ tetrahydropyrido[3,2,1‐ jk ]carbazol‐6‐ones

Tetrahydrocarbazoles 4 obtained from phenylhydrazines and cyclohexanones gave by cyclocondensation with 2‐substituted malonates 5 in all cases 4‐hydroxy‐8,9,10,11‐tetrahydropyrido[3,2,1‐ jk ]carbazol‐6‐ones 6 by attack at the nitrogen and the aromatic ring of tetrahydrocarbazoles 4 ; the direction of the cyclization was not dependent on substituents either in the aromatic or the saturated ring; isomeric pyridocarbazoles could not be isolated. Electrophilic substitutions of pyridocarbazoles 6 under mild conditions took place exclusively at the 5‐position and gave pyridocarbazolediones 9 , 10 , 11 with 5‐nitro‐, 5‐hydroxy or 5‐chloro‐substituents. Exchange of the chloro substituent in 11 gave 5‐azido‐ and 5‐amino products 12 , 14 or 16 . Reactions at the aromatic ring were not observed. Chlorination of 4‐hydroxypyridocarbazoles 6 with phosphoryl chloride by nucleophilic substitution took place exclusively at the 4‐position and gave 4‐chloropyridocarbazolones 17 , which were further reacted to azides and amines 18 , 19 . J. Heterocyclic Chem., (2010).