反应详情

温度

40 °C

9 g of 2,5-dihydroxy-1,4-dioxane-2,5-dimethanol is introduced into 60 ml of dioxane and the suspension is taken to about 70° C. for 15 minutes then returned to ambient temperature. 20 ml of 3,4-dihydro 2H-pyran and 300 mg of monohydrated paratoluene sulphonic acid are then added and the temperature is maintained at about 40° C. then the whole is left for 16 hours at ambient temperature. The reaction medium is poured into a mixture of 300 ml of saturated sodium bicarbonate solution +10 ml of triethylamine and extraction is carried out 4 times with methylene chloride. The organic phase is washed with salt water and dried. After purification by passage through silica, eluting with cyclohexane-ethyl acetate: 8-2 with 0.5% of triethylamine, 17 g of expected product (pale yellow syrup) is obtained.

1. customthen returned to ambient temperature
2. waitthe whole is left for 16 hours at ambient temperature
3. washThe organic phase is washed with salt water
4. customdried
5. customAfter purification by passage through silica
6. washeluting with cyclohexane-ethyl acetate