Benzyl Bromide → Diethyl 11-(benzyloxy)undecylphosphonate

Participants

Reaction Steps

Diethyl 11-hydroxyundecylphosphonate (4.0 g, 13.0 mmol) and 18-crown-6 (spatula tip) were added to anhydrous tetrahydrofuran under inert atmosphere. Sodium hydride (312 mg, 13.0 mmol) was added and the solution allowed to stir for 10 minutes. Benzyl bromide (2.4 mL, 19.5 mmol) was then added and the reaction stirred at reflux for 4 hours. After cooling to room temperature, dichloromethane was added and the mixture washed with water and brine. The organic layer was collected, dried over magnesium sulfate, and concentrated under reduced pressure to yield a liquid. Column chromatography (stationary phase:silica, mobile phase:ethyl acetate) was used to isolate the desired product (Rf=0.70, ethyl acetate) as a clear oil (2.173 g, 42% yield). 1H NMR (500.13 MHz, CD2Cl2) δ 7.36-7.29 (m, 4H), 7.29-7.23 (m), 4.47 (2H), 4.10-3.97 (m, 4H), 3.45 (t, J=6.62 Hz, 2H), 1.72-1.62 (m, 2H), 1.62-1.48 (m, 4H), 1.40-1.20 (m, 20H). 13C{1H} NMR (100.62 MHz, CD2Cl2) δ 139.4, 128.6 (2C), 127.9 (2C), 127.7, 73.03, 70.88, 61.57 (d, J=6.4 Hz, 2C), 30.95 (d, J=16.8 Hz), 30.17, 29.94, 29.91, 29.85, 29.75, 29.48, 26.58, 25.91 (d, J=139.8 Hz), 22.78 (d, J=5.3 Hz), 16.68 (d, J=5.9 Hz, 2C). 31P{1H} NMR (202.45 MHz, CD2Cl2): δ 32.83. Analysis calculated (found) %: C 66.30 (65.66), H 9.86 (9.95). MS (ESI, m/z): 399 (M+, 100%). Exact mass calculated (found) for [M+H]+, m/z): 399.2659 (399.2671).

Provenance & Evidence