3,5-Dimethyl-4-[2-(methyloxy)-5-nitrophenyl]isoxazole → Ethyl 7-(3,5-dimethyl-4-isoxazolyl)-4-hydroxy-6-(methyloxy)-3-quinolinecarboxylate

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Reaction Steps

Diethyl({[3-(3,5-dimethyl-4-isoxazolyl)-4-(methyloxy)phenyl]amino}methylidene)propanedioate (for a preparation see Intermediate 3) (35 g, 90 mmol) was added in small portions over 10 min to boiling diphenyl ether (500 ml)—vigorous effervescence results. The mixture was heated at reflux for 20 min, the heater was switched off and removed from the vessel and the solution allowed to cool in air over 2 h to 40° C., giving some precipitation of a brown granular solid. The mixture was diluted with ether (300 ml) and allowed to stand overnight, then filtered and the solid washed with ether (2×200 ml) and dried to give ethyl 7-(3,5-dimethyl-4-isoxazolyl)-4-hydroxy-6-(methyloxy)-3-quinolinecarboxylate (28.4 g, 83 mmol, 92% yield). LCMS (formate) Rt 0.73 min, MH+ 343

Provenance & Evidence