Novel method for preparing 3-O-benzyl-1, 2-O-isopropylidene-alpha-L-furan idose
A kind of technology of idose and isopropylidene, applied in the field of preparing 3-O-benzyl-1
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Embodiment 1
[0028] Preparation of 3-O-benzyl-1,2-O-isopropylidene-α-D-glucofuranose III
[0029] Step a: Preparation of 3-O-benzyl-1,2:5,6-di-O-isopropylidene-α-D-glucofuran
[0030] Under the protection of argon, 1 liter of tetrahydrofuran and 64 grams of 60% sodium hydride were successively added into a 5 L four-neck reaction flask, and cooled to 0° C. to 5° C. in an ice-water bath. Add dropwise a mixed solution of 315 g of 1,2:5,6-di-O-isopropylidene-α-D-glucofuran and 1 liter of tetrahydrofuran, control the temperature from 0°C to 10°C, and keep the reaction at about 0°C for five Hour. 220 ml of benzyl bromide was added dropwise, the temperature was controlled from 0°C to 10°C, 20 g of tetrabutylammonium bromide was added, the ice-water bath was removed, and the reaction was allowed to rise to room temperature naturally, and stirring was continued until the reaction was complete. Add a small amount of methanol dropwise to quench the reaction, concentrate under reduced pressure to re...
Embodiment 2
[0035] Preparation of 6-O-benzoyl-3-O-benzyl-1,2-O-isopropylidene-α-D-glucofuranose IV and 6-O-benzoyl-3-O-benzyl- 1,2-O-isopropylidene-5-O-methanesulfonyl-α-D-glucofuranose V
[0036] 96.5 g of compound III was dissolved in 500 ml of pyridine, cooled to -10°C in an ice-salt bath, and a solution of 36.89 ml of benzoyl chloride in 40 ml of dichloromethane was added dropwise. The reaction temperature is controlled at -10 to 0°C. After the reaction was complete, the reaction mixture was directly put into the next reaction without separation and purification.
[0037] After cooling to 0°C in an ice-water bath, 26 ml of methanesulfonyl chloride was slowly added dropwise to the above reaction mixture, and stirred overnight. After the reaction is complete, pour the reaction solution into about 2 liters of warm water at 55°C to 60°C. After cooling, white crystals are precipitated, filtered and dried, and then recrystallized with ethanol. After drying, 114.8 g of compound V were obt...
Embodiment 3
[0041] Preparation of 5,6-epoxy-3-O-benzyl-1,2-O-isopropylidene-α-L-furanoidose VI
[0042] Dissolve 50 g of compound V in 300 ml of dioxane, slowly add a solution of 29 g of potassium hydroxide and 100 ml of water into the reaction solution at room temperature, and stir at room temperature after the addition is complete until the reaction is complete. The reaction mixture was cooled with an ice-water bath, and neutralized to neutrality by slowly adding hydrochloric acid dropwise. The low boiling point solvent was removed under reduced pressure, and the resulting mixture was extracted with ethyl acetate. The organic phases were combined, washed successively with saturated sodium bicarbonate solution and saturated sodium chloride solution, dried over anhydrous sodium sulfate, and concentrated to obtain 30.5 g of crude compound VI. The crude product was directly subjected to the next reaction without further purification.
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