反应详情

A solution of 15 (1.02 g, 1.93 mmol) in acetonitrile (24 mL) was treated with 50% aqueous hypophosphorous acid (11 mL) and stirred at reflux for 1.5 hr. After cooling, the acetonitrile was removed on a rotary evaporator. The residue was diluted with water (100 mL) and extracted with ethyl acetate (150 mL). The organic layer was washed with water (100 mL), saturated sodium bicarbonate (100 mL) and water (100 mL). The organic layer was dried over sodium sulfate and stripped. The crude product was purified by chromatography on silica (60 g) with 1% ethyl acetate in hexane (2 L). The relevant fractions were stripped and the residue was taken up in ethanol (12 mL) and stirred at 60° C. on a water bath for 30 min. The resulting slurry was allowed to cool overnight. The crystals were collected by filtration, washed with cold ethanol and dried in a vacuum oven at 65° C. to produce pure B4 (0.69 g, 85%).

1. temperatureat reflux for 1.5 hr
2. temperatureAfter cooling
3. customthe acetonitrile was removed on a rotary evaporator
4. additionThe residue was diluted with water (100 mL)
5. extractionextracted with ethyl acetate (150 mL)
6. washThe organic layer was washed with water (100 mL), saturated sodium bicarbonate (100 mL) and water (100 mL)
7. dry with materialThe organic layer was dried over sodium sulfate
8. customThe crude product was purified by chromatography on silica (60 g) with 1% ethyl acetate in hexane (2 L)
9. stirringstirred at 60° C. on a water bath for 30 min
10. temperatureto cool overnight
11. filtrationThe crystals were collected by filtration
12. washwashed with cold ethanol
13. customdried in a vacuum oven at 65° C.