Ethyl Acetate → 8,10a-Dihydro-7,9-dimethyl-6-oxo-6H-pyrano(3,2-b:5,4-c') dipyridine-10-carboxylic acid ethyl ester

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Reaction Conditions

Reaction Steps

Diethyl 1,4-dihydro-4-(3-hydroxypyridyl)-2,6-dimethyl-3,5-pyridine dicarboxylate (17.3 grams; 0.05 mole) was nearly dissolved in 250 ml toluene heated at 140° C. Diazabicyclo(5.4.0) undec-7-ene (8.3 grams; 8.2 ml; 0.05 mole) dissolved in 20 ml toluene was added and the reaction mixture refluxed for a period of 22 hours at 180° C. (bath temperature). The black solution was cooled and concentrated to afford 23.3 grams of a black paste. High pressure liquid chromatography (HPLC) using ethyl acetate yielded 8.3 grams of a yellow solid, m.p. 100°-150° C. Two recrystallizations from 2-propanol gave 4.5 grams (30%) of fluorescent yellow material, m.p. 150°-160° C.

Provenance & Evidence