The reaction of nicotinic acid (I) with SOCl2 gives the corresponding acyl chloride (II), which is condensed with 2-methylpyrazolo[1,5-a]pyridine (III) by heating at 160-80 C or in refluxing dioxane, yielding 2-methyl-3-(3-pyridylcarbonyl)pyrazolo[1,5-a]pyridine (IV). Finally, this compound is hydrogenated with H2 over Pd/C in ethanol at 13 Atm. pressure and 55-8 C.
By demethylation of 5-methoxy-3-[4-(4-phenyl-1,2,3,6-tetrahydropyridin-1-yl)butyl]-1H-indole (I) with diisobutylaluminum hydride (DBH) in hot toluene. The methylated compound (I) can be obtained by two similar ways: a) By condensation of 3-(4-chlorobutyl)-5-methoxy-1H-indole (II), or 3-(4-bromobutyl)-5-methoxy-1H-indole (III) with 4-phenyl-1,2,3,6-tetrahydropyridine (IV) in acetonitrile at room temperature. b) By condensation of 4-(3-indolyl)butyric acid (V) with 4-phenyl-1,2,3,6-tetrahydropyridine (IV) by means of carbonyldiimdazole (CDI) in THF yielding 1-[4-(3-indolyl)butyryl]-4-phenyl-1,2,3,6-tetrahydropyridine (VI), followed by reduction of the carbonyl group of (VI) with LiAlH4 in THF.