Methane → Pravastatin

From the broth 3.7 g pravastatin dibenzylamine salt crude product was produced by the method given in Example 4, from which after recrystallization 2.9 g pravastatin dibenzylamine salt was obtained. The recrystallized pravastatin dibenzylamine salt was suspended in 45 ml ethanol, then under stirring 110 mole % sodium hydroxide was added by the feeding of 1M ethanolic sodium hydroxide solution. Stirring of the solution is continued for half an hour, then 0.3 g charcoal was added into it and stirred for another half an hour. The solution was filtered, and the filtrate was concentrated to 15 ml. Then 60 ml acetone was added to the concentrate at 56-60° C. The solution obtained was cooled to room temperature, then kept overnight at +5° C. Subsequently, the precipitate was filtered, then washed with 2×20 ml acetone, 2×20 ml ethyl acetate and 2×20 ml n-hexane, and finally dried in vacuum. The resulting 1.7 g crude pravastatin was dissolved in ethanol, then clarified with charcoal and crystallized from an ethanol-ethyl acetate mixture. In this way 1.54 g pravastatin was obtained that was identical with the product of Example 2.