合成路线1

The condensation of 3,4-difluoroaniline (I) with 3-chloropropionyl chloride (II) and pyridine in hot acetone give the anilide (III), which is cyclized by means of AlCl3 at 110?C, yielding 6,7-difluoro-1,2,3,4-tetrahydroquinolin-2-one (IV). The reaction of (IV) with POCl3 and dimethylformamide affords the carbaldehyde (V), which is oxidized and aromatized by means of KMnO4 and KOH in water, providing 2-chloro-6,7-difluoroquinoline-3-carboxylic acid (VI). The reaction of (VI) with SOCl2 in chloroform gives the corresponding acyl chloride (VII), which is condensed with the magnesium salt of the malonic acid monoethyl ester (VIII) in THF to yield the 3-oxopropanoate (IX). The reaction of (IX) with dimethylformamide dimethylacetal (DMF) in hot ethyl acetate affords the 3-(dimethylamino)acrylate (X), which is cyclized by means of methylamine in ethanol to provide 7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[g][1,8]naphthyridine-3-carboxylic acid ethyl ester (XI). The hydrolysis of (XI) with HCl in hot HOAc gives the corresponding carboxylic acid (XII) (1), which is condensed with 1-(4-fluorophenyl)piperazine (XIII) by heating at 90?C to yield the adduct (XIV). Finally, this compound is treated with choline hydroxide (XV) in methanol to afford the target choline salt.