Tributylamine → 6-(6-cyano-2,2-dimethyl-2H-1-benzopyran-4-yl)-3-pyridinecarboxylic acid

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Reaction Steps

5.06 g of benzyl 6-(6-cyano-2,2-dimethyl-2H-1-benzopyran-4-yl)-3-pyridinecarboxylate were heated at 100° C. with 7.8 ml of tributylamine, 244 mg of 10% palladium-on-charcoal and 0.9 ml of formic acid. After 12 hours a further 7.8 ml of tributylamine and 10 ml of formic acid were added. After 24 hours a further 2 ml of tributylamine and 3 ml formic acid were added. After 26 hours a further 170 mg of 10% palladium-on-charcoal, 2 ml tributylamine and 3 ml of formic acid were added. After 28 hours the mixture was evaporated and filtered. The filtrate was evaporated and the residue obtained was chromatographed on silica gel using ethyl acetate/petroleum ether (1:2) and ethyl acetate for the elution. There were obtained 1.4 g of 6-(6-cyano-2,2-dimethyl-2H-1-benzopyran-4-yl)-3-pyridinecarboxylic acid which was used without further purification.

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