B. P. Nikam, T. Kappe
2017
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Journal
Journal of Heterocyclic Chemistry
Abstract
A simple and efficient method has been described for the synthesis of acetyl and iodo derivatives of 4-hydroxy-6-phenyl-6H-pyrano[3,2-c]pyridine-2,5-diones and 4-hydroxy-1-phenylpyridin-2(1H)-ones . Compounds with phenyl and alkyl substituent at C(7) and C(8), respectively, can be easily acetylated by refluxing in a mixture of acetic acid and polyphosphoric acid to give 3-acetyl-4-hydroxy-6-phenyl-6H-pyrano[3,2-c]pyridine-2,5-diones in excellent yields. Compounds and can be iodinated with iodine and anhydrous sodium carbonate in boiling dioxane to give 4-hydroxy-3-iodo-6-phenyl-6H-pyrano[3,2-c]pyridine-2,5-diones and 4-hydroxy-3-iodo-1-phenylpyridin-2(1H)-ones , respectively, in good yields. The structures were confirmed using infrared, nuclear magnetic resonance , and elemental analysis.