Diphenyl Ether → Ethyl 4-Oxo-4H-pyrimido[2,1-a]isoquinoline-3-carboxylate

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Reaction Steps

A stirred mixture of diethyl isoquinolylaminomethylenemalonate (32.0 g., 0.0986 mole) and diphenyl ether (125 ml.) under nitrogen was heated at a temperature of 235° for 15 minutes. The solid, m.p. 183°-184°, obtained upon cooling and dilution with Skellysolve B was recrystallized from ethanol to give salmon crystals (22 g., 83% yield), m.p. 189°-191°. An analytical sample, recrystallized from ethanol, had m.p. 190°-192°.

Provenance & Evidence