Hydrochloric Acid → 6-cyano-2,2-dimethyl-4-{1,2-dihydro-2-oxo-4-(1,3-dihydroxypropyl)-1-pyridinyl}-2H-benzo[b]pyran

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Reaction Steps

In 50 ml of dioxane, is dissolved 3.87 g of 6-cyano-2,2-dimethyl-4-{1,2-dihydro-2-oxo-4-(1-hydroxy-2-ethoxycarbonylethyl)-1-pyridinyl}-2H-benzo[b]pyran obtained in Example 31. Then, 50 ml of an aqueous solution containing 3.71 g of sodium borohydride is added at room temperature and reacted at room temperature for one hour. After stopping the reaction by adding 100 ml of 2M aqueous hydrochloric acid, the reaction mixture is extracted with ethyl acetate. The organic layer is washed with saturated aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate. The inorganic matter is filtered off and the filtrate is concentrated under reduced pressure. The residue is purified by silica gel column chromatography using 1/10 mixture of methanol/methylene chloride as a developing solvent. Thus, 2.32 g of 6-cyano-2,2-dimethyl-4-{1,2-dihydro-2-oxo-4-(1,3-dihydroxypropyl)-1-pyridinyl}-2H-benzo[b]pyran is obtained.

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