反应详情

To a solution of diethyl phosphonate (xii) (745 mg; 1.8 mmol) in dichloromethane (8 mL) at 0° C. was slowly added bromotrimethylsilane (2 mL; 15.2 mmol). The reaction was gradually warmed to room temperature and the following day the solution was evaporated. The residue was redissolved in dichloromethane (10 mL), evaporated and the process repeated once more. Methanol (10 mL) was added to the residue and the solution stirred at room temperature for 30 minutes, then the solution was filtered and concentrated. The oily residue was triturated with 1:1 ether-hexanes and the orange solid collected by filtration. Finally, the orange solid was boiled in dichloromethane (5 mL), cooled and filtered to yield pure phosphonic acid (xiii) (512 mg, 80%) as a colorless solid: 1H NMR (400 MHz, CD3OD) δH 2.71 (dt, J=14, 10 Hz, 1H, CHPh), 3.13 (ddd, J=4, 8, 14 Hz, 1H, CHPh), 3.89 (ddd, J=4, 10, 14 Hz, NCHP), 6.86 (dd, J=3.5, 5 Hz, 1H, Ar—H), 7.07-7.15 (m, 6H, Ar—H), 7.53 (dd, J=1.5, 5 Hz, 1H, Ar—H).

1. customat 0° C.
2. customthe following day the solution was evaporated
3. dissolutionThe residue was redissolved in dichloromethane (10 mL)
4. customevaporated
5. additionMethanol (10 mL) was added to the residue
6. filtrationthe solution was filtered
7. concentrationconcentrated
8. customThe oily residue was triturated with 1:1 ether-hexanes
9. filtrationthe orange solid collected by filtration
10. temperaturecooled
11. filtrationfiltered