合成路线1

The reaction of 3-chlorotetrafluoropyridine (I) with sodium tert-butoxide in THF gives 4-(tert-butoxy)-3-chloro-2,5,6-trifluoropyridine (II), which is dechlorinated with H2 over Pearlman's catalyst in methanol yielding 4-(tert-butoxy)-2,3,6-trifluoropyridine (III). The methylation of (III) with methyl iodide and lithium diethylamide (LDA) in THF affords 4-(tert-butoxy)-2,3,6-trifluoro-5-methylpyridine (IV), which is treated with hydrazine in refluxing propanol to give 4-(tert-butoxy)-2,5-difluoro-3-methylpyridine (V). The condensation of (V) with 2-bromo-2-cyclopropylacetopnitrile (VI) by means of LDA in THF yields the expected condensation product (VII), which is treated with TFA to eliminate the tert-butyl protecting group and with POCl3 in DMF to afford the 4-chloropyridyl derivative (VIII). The hydrolysis of the nitrile group of (VIII) with HCl in ethanol gives the corresponding acetate ester (IX), which is reduced with LiAlH4 in THF to the alcohol (X). The oxidation of (X) with oxalyl chloride in DMSO/dichloromethane yields the aldehyde (XI), which is cyclized with diethyl malonate (XII) by means of piperidine in refluxing acetic acid, followed by heating at 220 C C in Dowtherm to afford 8-chloro-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-3-carboxylic acid ethyl ester (XIII). The condensation of (XIII) with 7(S)-(tert-butoxycarbonylamino)-5-azaspiro[2.4]heptane (XIV) by means of triethylamine in DMF gives the expected condensation product (XV), which is methylated with methyl iodide and sodium hexamethyldisylazane (Na-HMDS) in THF yielding the N-methyl derivative (XVI). The hydrolysis of the ester group of (XVI) with LiOH in THF/water provides the corresponding free acid (XVII), which is finally deprotected with HCl in acetic acid. The synthesis of the intermediate 7(S)-(tert-butoxycarbonylamino)-5-azaspiro[2.4]heptane (XIV) has already been described in the first synthesis of compound no. 268134 (see scheme 26813401a).