Alkylation of 4-hydroxy-5-methoxy benzoic acid methyl ester (I) with 3-chloropropyl p-toluene sulfonate (III) by means of K2CO3 and methyl-tricapryl ammonium chloride (Aliquat 128) in refluxing acetone affords compound (III), which is then nitrated by means of HNO3 in HOAc to furnish 2-nitro derivative (IV). Reduction of the nitro moiety of (IV) by means of Fe in H2O/MeOH in the presence of ammonium chloride yields 2-amino compound (V), which is subjected to reaction with refluxing dimethylformamide dimethylacetal (VI) to provide amidine (VII). Condensation of (VII) with acetonitrile by means of n-BuLi in hexane/THF/HOAc gives substituted quinoline-carbonitrile (IX), whose hydroxyl group is replaced by a chlorine by treatment of (IX) with refluxing POCl3 to afford compound (X). Coupling of (X) with 2,4-dichloro-5-methoxyaniline (XI) in 2-ethoxyethanol in the presence of pyridine hydrochloride yields compound (XII), which is finally converted into the desired compound by condensation with 1-methylpiperazine (XII) by means of NaI in refluxing ethylene glycol dimethyl ether.
The alkylation of 4-hydroxy-3-methoxybenzoic acid methyl ester (I) with 3-(4-morpholinyl)propyl chloride (II) and tetrabutylammonium chloride in refluxing butanone gives 3-methoxy-4-[3-(4-morpholinyl)propoxy]benzoic acid methyl ester (III), which is nitrated with HNO3 in hot acetic acid to yield 5-methoxy-4-[3-(4-morpholinyl)propoxy]-2-nitrobenzoic acid methyl ester (IV). The reduction of (III) with H2 over Pd/C in methanol/ethyl acetate to afford the corresponding 2-amino ester (V), which is condensed with dimethylformamide dimethylacetal (VI) by heating at 100 C to provide the 2-(dimethylaminomethyleneamino) derivative (VII). The cyclization of (VII) with acetonitrile (VIII) by means of BuLi and CO2 in THF gives 6-methoxy-7-[3-(4-morpholinyl)propoxy]-4-oxo-1,4-dihydroquinoline-3-carbonitrile (IX), which is treated with refluxing SOCl2 to yield the 4-chloroquinoline derivative (X). Finally, this compound is condensed with 2-bromo-5-methoxyaniline by means of pyridine hydrochloride in 2-ethoxyethanol or NaH in THF (or DMF).