Manufacturing Process
100 g proscillaridin (from Scilla maritima L., enzymatic hydrolysis) was dissolved in 500 ml dry tetrahydrofuran, mixed with 100 ml of triethyl ortoformiate and 50 mg p-tholuene sulfonic acid and stirred for 15 minutes at 20°C.
It was put into a separating funnel and shook with 1 L ethyl acetate and 200 ml of 5% sodium hydroxide. The an organic layer was separated, with 2-3 L water washed (portions 400-500 ml), dried over sodium sulfate and distilled in vacuum to dryness at about 60°C. 121.2 g crude proscillaridin-2,3-ethyl ortoformiate yielded. It was dissolved in 1 L dimethylformamide, mixed with 200 ml methyl iodide and stirred with 20 g 55-60% suspension of sodium hydride at 20°C for 1 hour. 14 L ethyl acetate was added, 5 times with 1-2 L water shook and the organic layer was distilled to 1/4 of volume. The solution of proscillaridin-2,3-ethyl ortho-formiate-4-methyl ester obtained (about 1 L) was mixed with 2 L 0.002 N HCl and stood for 2 hours at 20°C. Then it was neutralized with 0.1 N sodium hydroxide and distilled in vacuum to about 1 L. The solution was shook with 2 L chloroform and 1 L water, organic layer was separated, water layer was 2 times was extracted with still 1 L chloroform and the pooled organic phase dried over sodium sulfate. Then the solvent was removed and 147 g of obtained product was purified by chromatography on silica gel in system chloroform/acetone 4:1.
63 g of crude amorphic 4-O-methylproscillaridin was isolated and recrystallized from methylene chloride/ethyl acetate to give 49.3 g (53% yield) the desired product; MP: 213°-217°C.
