A new synthesis of dibenzo[b,g][1,5]naphthyridine-6,12(5H,1H)dione (epindolidione) |
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Authors: | C K Kim C A Maggiulli |
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Abstract: | A new convenient synthesis of dibenzob,g]1,5]naphthyridine-6,12(5H,11H)dione starting from N-phenylglycine ethyl ester is described. Ester condensation of N-phenylglycine ethyl ester with diethyl oxalate followed by reaction with aniline under acid catalysis gave a mixture of diethyl dianilinomaleate and diethyl dianilinofumarate in 54% yield. Upon heating this mixture in a high-boiling inert solvent, 3-anilino-2-ethoxycarbonyl-4-quinolone was obtained in 72% yield. Final ring closure of the quinolone derivative using polyphosphoric acid gave the epindolidione. |
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