反应详情

To Intermediate 4 (34 g) in ethanol (1070 ml) at −5° C. was added sodium borohydride (9.86 g). A solution of 4M hydrogen chloride in 1,4-dioxan (20 ml) was then added dropwise. Periodically further portions of 4M hydrogen chloride in 1,4-dioxan (2×5 ml, 1×10 ml) and sodium borohydride (2 g) were added. After 3 h, concentrated sulphuric acid (11 ml) was added and the mixture warmed to room temperature for 2 h. Saturated aqueous sodium bicarbonate (300 ml) was then added and the ethanol and dioxan removed in vacuo. The residue was diluted with water (500 ml) and extracted with ethyl acetate (3×500 ml). The combined extracts were washed with brine and dried (MgSO4). The solvent was removed in vacuo and the residue purified by flash chromatography on silica gel 9385 eluting with ether, to give the title compound (21 g). Mass spec. MNH4+ (found) 378 MNH4+ (calculated) 378

1. customthe ethanol and dioxan removed in vacuo
2. additionThe residue was diluted with water (500 ml)
3. extractionextracted with ethyl acetate (3×500 ml)
4. washThe combined extracts were washed with brine
5. dry with materialdried (MgSO4)
6. customThe solvent was removed in vacuo
7. customthe residue purified by flash chromatography on silica gel 9385 eluting with ether