Methanol → Methanol, magnesium salt (2:1)

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Reaction Conditions

Reaction Steps

The procedure is carried out as described in Raju et al, Organic Process Research & Development 2006, 10, 33-35, which is hereby incorporated by reference in its entirety. A solution of magnesium methoxide was prepared by adding magnesium turnings (1.31 g, 0.054 mol) and dichloromethane (5 mL) to methanol (150 mL) and stirring under nitrogen atmosphere for 2-3 hours, at 40-45° C. The solution was cooled to 5-10° C. and added to a stirred mixture of esomeprazole (42.0 g, 0.121 mol) and methanol (150.0 mL), and stirring was maintained for 3 hours. Water (2.0 mL) was added and stirring was continued for 1 hour and the solution was filtered. The mother liquor was distilled under reduced pressure at 35° C. Acetone (400 mL) was added and the mixture was stirred for 1 hour at 25-35° C. The precipitate was filtered and washed with acetone (200 mL), dissolved in methanol (222 mL) and water (8 mL) and stirred for about 30 minutes at 25-30° C. and filtered. The filtrate was suspended in water and stirred at 0-5° C. for about 45 minutes, filtered, washed with water (300 mL) and dried under reduced pressure to yield esomeprazole magnesium salt.

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