2-(3-Chloropropyl)-2-methyl-1,3-dioxolane → 1,3-Dioxolane, 2-(3-methoxypropyl)-2-methyl-

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To a solution of sodium methoxide prepared by the addition of 0.8 g of sodium to 35 mL of methanol was added 5-chloro-2-pentanone ethylene ketal (3 g, 180 mmol). The mixture was heated in a steel bomb at 100° C. for 18 hours. The methanol was removed by evaporation under reduced pressure and the residue was extracted into 20 mL of ether. The ether extract was washed with water, saturated saline solution and dried over magnesium sulfate. Evaporation of the ether yielded 1.6 grams of 5-methoxy-2-pentanone ethylene ketal. This was stirred in 10 mL of 75% formic acid for 24 h at room temperature. The mixture was neutralized with sodium bicarbonate and extracted with 50 mL of ether. The ether extract was washed with water, saturated saline solution and dried over magnesium sulfate. Evaporation yielded 1.2 g of the desired ketone as an oil. Step B: Preparation of 1-(R)-(3,4-dihydroxyphenyl)-2-(1-methyl-4-methoxybutylamino)ethanol oxalate salt

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