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温度

0 °C

Butylphosphinic acid (2.0 g, 16 mmol) in 80 mL of dry dichloromethane was cooled to 0° C. under an atmosphere of nitrogen. Triethylamine (6.7 g, 66 mmol) was added followed by trimethylsilyl chloride (58 mL, 58 mmol, 1.0 M in dichloromethane). The mixture was stirred at 0° C. for 10 minutes and dibenzyl 2-methylenepentanedioate (2)(6.4 g, 20 mmol) in 20 mL of dichloromethane was added. The cold bath was removed and the reaction warmed to room temperature and stirred overnight. The mixture was then cooled to 0° C. and quenched by the slow addition of 5% hydrochloric acid. The dichloromethane layer was then removed and washed with 5% hydrochloric acid and with brine. The organic layer was dried (MgSO4) and evaporated to give a clear light golden liquid. The liquid was purified by flash chromatography and eluted with 3:1 hexane/ethyl acetate containing 5% acetic acid. The desired fractions were combined and evaporated to give butyl[2,4-di(benzyloxycarbonyl)butyl]phosphinic acid (3,R=n-butyl, R1=H) (2.9 g, 40%) as a clear and colorless oil. Rf0.12 (3:1, Hex./EtOAc 5% AcOH).

1. customThe cold bath was removed
2. temperaturethe reaction warmed to room temperature
3. stirringstirred overnight
4. temperatureThe mixture was then cooled to 0° C.
5. customquenched by the slow addition of 5% hydrochloric acid
6. customThe dichloromethane layer was then removed
7. washwashed with 5% hydrochloric acid and with brine
8. dry with materialThe organic layer was dried (MgSO4)
9. customevaporated
10. customto give a clear light golden liquid
11. customThe liquid was purified by flash chromatography
12. washeluted with 3:1 hexane/ethyl acetate containing 5% acetic acid
13. customevaporated