反应详情

The glycine (Intermediate 54, 1 g, 5.1 mmol) was dissolved in acetic acid (10 ml) and water (1 ml) and cooled to ~5° C. Sodium nitrite (0.37 g, 5.4 mmol) in water (1.3 ml) was added to the glycine solution dropwise, maintaining the temperature at or below 5° C. The reaction was stirred at this temperature for 1 h. Zinc (1.33 g, 20.3 mmol) was then added slowly to the reaction keeping the temperature below 4° C., and the reaction was stirred for 1 h. The reaction mixture was poured into water (100 ml) and extracted with ethyl acetate (3×100 ml). The combined organic extracts were washed with water (2×100 ml) followed by saturated aqueous sodium bicarbonate (1×100 ml) then water (100 ml), dried (Na2SO4) and concentrated in vacuo to give an orange oil (1.06 g). The crude material was purified by chromatography on silica (Merck 9385, 28 g) eluted with ether-hexane 1:4 to give the title compound (Intermediate 55, 453 mg, 40%).

1. temperaturemaintaining the temperature at or below 5° C
2. customthe temperature below 4° C.
3. stirringthe reaction was stirred for 1 h
4. extractionextracted with ethyl acetate (3×100 ml)
5. washThe combined organic extracts were washed with water (2×100 ml)
6. dry with materialwater (100 ml), dried (Na2SO4)
7. concentrationconcentrated in vacuo