Reaction Steps
Bromotrimethylsilane (5 mL, 38 mmol) was added to a cold (0° C.) solution of 12b (287 mg, 0.46 mmol) in CHCl3 (20 mL). The mixture was stirred for 24 h at room temperature, and then concentrated under reduced pressure. The residue was taken up in water (15 mL), stirred for 2 h at room temperature, and subjected to lyophilization. The residue was purified on a C18 column (0.1 M aqueous NH4HCO3 solution) to afford ammonium phosphonate 13b (132 mg, 72% yield). White solid, mp 220-223° C.; [α]D20=−55.3 (c=1.5, H2O); IR (neat) 3512, 2901, 1716, 1101 cm−1; 1H NMR (600 MHz, D2O) δ 6.12 (1 H, d, JP-2=19.0 Hz), 4.12 (1 H, d, J=6.9 Hz), 3.80 (1 H, dd, J=10.0, 5.0 Hz), 3.71-3.62 (1 H, m), 3.41 (1 H, br s), 2.62-2.59 (1 H, m), 2.28-2.23 (1 H, m), 1.91 (3 H, s), 1.46-1.44 (3H, m), 1.34-1.28 (1 H, m), 0.77 (3 H, t, J=7.3 Hz), 0.72 (3 H, t, J=7.3 Hz); 13C NMR (150 MHz, D2O) δ 174.5, 156.6, 134.3 (C-1, d, JP-1=168 Hz), 132.7, 84.2, 76.3, 55.2, 51.0, 30.8, 25.5, 25.2, 21.8, 8.6, 8.2; 31P NMR (162 MHz, D2O) δ10.92; HRMS calcd for C14H26N4O5P [M+H−2 NH4]+: 361.1652, found: 361.1637. Anal. Calcd for C14H33N6O5P.(2H2O): C, 38.88; H, 8.62; N, 19.43. Found: C, 38.74; H, 8.71; N, 19.39.
