The alkylation of 4-(N-acetyl-N-ethylamino)-2-hydroxyacetophenone (I) with allyl bromide (II) by means of K2CO3 in DMF gives the allyl ether (III), which is isomerized by refluxing in diethylaniline to 4-(N-acetyl-N-ethylamino)-3-allyl-2-hydroxyacetophenone (IV) The reduction of (IV) with H2 over Pd/C in ethanol affords the corresponding propyl derivative (V), which is deacetylated with HBr in refluxing acetic acid water to 4-(ethylamino)-3-propyl-2-hydroxyacetophenone (VI). The addition of (VI) dimethyl acetylenedicarboxylate (VII) in refluxing ethanol affords the aminomaleate (VIII), which by cyclization witn polyphosphoric acid at 100 C gives methyl 1-ethyl-6-acetyl-7-hydroxy-4 oxo-8-propyl-4H-quinoline-2-carboxylate (IX). The condensation of (IX) with diethyl oxalate in DMF by means of NaH results in the ester of the final product (X), which is then hydrolyzed with NaHCO3 iin refluxing ethanol.