4H-pyran-4-one → 8-(4-Oxo-1,4-dihydropyridin-1-yl)-4,4a,5,6-tetrahydrobenzo[h]cinnolin-3(2H)-one

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Reaction Steps

A stirred mixture of 8-amino-4,4a,5,6-tetrahydrobenzo[h]cinnolin-3(2H)-one hydrochloride (1.5 g) and 4H-pyran-4-one (0.84 g) in water (40 ml) was heated under reflux for 2 hours in a nitrogen atmosphere. The resultant solid was washed with dilute hydrochloric acid to give a crude product, 0.5 g. Purification by column chromatography (silica gel, 9:1 chloroform: methanol) gave the title compound 0.18 g, m.p. >300° C.

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