Hydrochloric Acid → 6-cyano-2,2-dimethyl-4-(1,2-dihydro-2-oxo-4-hydroxymethyl-1-pyridinyl)-2H-benzo[b]pyran

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Reaction Steps

In 4 ml of anhydrous tetrahydrofuran, is dissolved 350 mg of 6-cyano-2,2-dimethyl-4-(4-ethoxycarbonyl-1,2-dihydro-2-oxo-1-pyridinyl)-2H-benzo[b]pyran obtained in Example 21. Then, 0.50 ml of 2.0M solution of lithium borohydride in tetrahydrofuran is added to the solution at room temperature and reacted at room temperature for 1.5 hours. After stopping the reaction by adding 0.2M phosphate buffer, the insoluble matter is solubilized by adding 2N aqueous hydrochloric acid. Then, the reaction mixture is extracted with ethyl acetate. The organic layer is washed with saturated aqueous solution of sodium chloride and dried over anhydrous sodium sulfate. The inorganic matter is filtered off, and the filtrate is concentrated under reduced pressure. The residue thus obtained is purified by silica gel column chromatography using 1/20 mixture of methanol/methylene chloride as a developing solvent to obtain 163 mg of 6-cyano-2,2-dimethyl-4-(1,2-dihydro-2-oxo-4-hydroxymethyl-1-pyridinyl)-2H-benzo[b]pyran.

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