反应详情

Benzyl 3,5-dihydroxypentylcarbamate (7.3 g, 28.8 mmoles) is co-evaporated twice with anhydrous pyridine (100 mL each) and then is dissolved in anhydrous pyridine (300 mL). The solution is chilled in an ice bath, and 4,4′-dimethoxytritylchloride (9.8 g, 28.9 mmoles) is added. The reaction is allowed to warm to ambient temperature and is stirred for 16 hours. The yellow solution is then evaporated to near dryness, and the residue is dissolved in dry toluene (250 mL). The toluene mixture is chilled for 1 hour at 4° C., then filtered. The collected solid is washed with toluene (50 mL) and the combined toluene filtrates are evaporated to a dark yellow syrup. The syrup is dried in vacuo for at least 24 hours at ambient temperature. The crude product is purified on silica gel (500 mL bed volume) eluting with hexanes:ethyl acetate:triethylamine (90:5:5 [v/v/v], 300 mL, then 85:10:5 [v/v/v], 1000 mL, then 80:15:5 [v/v/v], 1000 mL, then 75:20:5 [v/v/v], 1000 mL, then 70:25:5 [v/v/v], 2000 mL, then 50:45:5 [v/v/v], 2000 mL). Fractions containing pure product by thin layer chromatography are pooled and evaporated to a pale yellow syrup. The syrup is dried well in vacuo. The yield is 15.4 g (96%).

1. temperatureThe solution is chilled in an ice bath
2. customThe yellow solution is then evaporated
3. dissolutionthe residue is dissolved in dry toluene (250 mL)
4. temperatureThe toluene mixture is chilled for 1 hour at 4° C.
5. filtrationfiltered
6. washThe collected solid is washed with toluene (50 mL)
7. customthe combined toluene filtrates are evaporated to a dark yellow syrup
8. customThe syrup is dried in vacuo for at least 24 hours at ambient temperature
9. customThe crude product is purified on silica gel (500 mL bed volume)
10. washeluting with hexanes:ethyl acetate:triethylamine (90:5:5 [v/v/v], 300 mL
11. additionFractions containing pure product by thin layer chromatography
12. customevaporated to a pale yellow syrup
13. customThe syrup is dried well in vacuo