A mixture of 2.00 g (5.39 mmol) of 6-methoxy-8-chloro-11-(1-methyl-4-piperidinyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ol in 87% aqueous sulfuric acid was stirred at room temperature and under an argon atmosphere. After 30 min 30 mL of trifluoromethanesulfonic acid was added and the mixture was heated to 115° C. One hour later the mixture was cooled to room temperature, poured onto ice, basified with 5% aqueous sodium hydroxide and extracted with methylene chloride (2×). The combined organic portions were washed with brine, dried over Na2SO4, filtered, and concentrated in vacuo to give 1.41 g of 8-chloro-5,11-dihydro-11-(1-methyl-4-piperidinylidene)-6H-benzo[5,6]cyclohepta-[1,2-b]pyridin-6-one. The material was recrystallized from ethyl acetate/isopropyl ether to give 1.12 g (61%) of the ketone as a granular solid: mp 181°-183° C.
