The condensation of aniline (I) with diethyl ethoxymethylenemalonate (II) by heating at 90 C gives diethyl anilinomethylenemalonate (III), which is cyclized to ethyl 4-hydroxyquinoline-3carboxylate (IV) by heating at 240 C in diphenyl ether-biphenyl. The reaction of (IV) with hot POCl3 affords ethyl-4-chloroquinoline-3-carboxylate (V), which is finally cyclized with 4-chlorophenylhydrazine (VIII) by heating at 105 C in xylene. (VIII) is prepared in the usual way starting from 4-chloroaniline (IX) by diazotation with NaNO2-HCl to 4-chlorophenyldiazonium chloride (X), and reduction with SnCl2-HCl.
The condensation of aniline (I) with diethyl ethoxymethylenemalonate (II) by heating at 90 C gives diethyl anilinomethylenemalonate (III), which is cyclized to ethyl 4-hydroxyquinoline-3-carboxylate (IV) by heating at 240 C in diphenyl ether-biphenyl. The reaction of (IV) with hot POCl3 affords ethyl 4-chloro-quinoline-3-carboxylate (V), which is finally cyclized with phenylhydrazine (VI) by heating at 105 C in xylene. (VI) is prepared in the usual way starting from aniline (I) by diazotation with NaNO2-HCl to phenyldiazonium chloride (VII), and reduction with SnCl2-HCl.