合成路线1

Alcoholysis of 3-methylpyridine-2-carbonitrile (I) with hot tert-butanol and H2SO4 gives the N-tert-butylcarboxamide (II), which is alkylated with 3-chlorobenzyl chloride (III) and BuLi in THF, yielding N-tert-butyl-3-[2-(3-chlorophenyl)ethyl]pyridine-2-carboxamide (IV). The reaction of (IV) with refluxing POCl3 and then with NaOH affords the corresponding nitrile (V), which is condensed with 1-methylpiperidin-4-ylmagnesium chloride (VI) in THF to give the ketone (VII). Cyclization of (VII) by means of either BF3 in HF or trifluoromethanesulfonic acid yields 8-chloro-11-(1-methylpiperidin-4-ylidene)-6,11-dihydro-5H-benzo[5,6]cyclohepta[1,2-b]pyridine (VIII), which is reacted with cyanogen bromide in benzene to give the N-cyano compound (IX). Finally, this compound is treated with HCl in refluxing acetic acid/water. Alternatively, 8-chloro-11-(1-methylpiperidin-4-ylidene)-6,11-dihydro-5H-benzo[5,6]cyclohepta[1,2-b]pyridine (VIII) is treated with ethyl chloroformate in hot toluene, affording the carbamate (X) (2), which is finally decarboxylated with KOH or NaOH in refluxing ethanol/water.