POLYCYCLIC AROMATIC ALKALOIDS .6. A REGIOSELECTIVE SYNTHESIS OF AZAFLUORENONE ALKALOIDS

6-Methoxyonychine 2 (8-methoxy-4-methyl-5H-indeno[1,2-b]pyridin-5-one) is obtained regioselectively from the biaryl 9 [2-(2-bromo-5-methoxyphenyl)-4-methyl-3-pyridinecarboxylic acid] via a Parham-type cyclisation. Alternatively, 9 can be converted to the unnatural isomer 8-methoxyonychine 11 by a simple two-step procedure (cyclisation and debromination).