Hydrochloric Acid → HCID 178454806, compound

Participants

Reaction Steps

Potassium di-tert-butyl phosphate (45 g) was dissolved in water (160 mL). Hydrochloric acid (1M, aq) was added until the pH was ˜3. The resultant precipitate was collected by filtration, washed with water, and dried under vacuum overnight to give di-tert-butyl phosphonic acid as a white solid. Then, to a suspension of i (18.68 g, 39.28 mmol), triphenylphosphine (17.51 g, 66.78 mmol), and di-tert-butyl hydrogen phosphate (10.73 g, 51.06 mmol) in THF and triphenylphosphine were suspended in anhydrous THF (200 mL). A solution of DIAD (13.5 g, 66.78 mmol) in THF (20 mL) was added dropwise. The mixture was stirred at room temperature and monitored by LCMS to completion then was concentrated under reduced pressure. Et2O (300 mL) was added and the mixture sonicated, resulting in a bright white solid, which was filtered, washed with Et2O (100 mL) and air dried. The filtrate also contained some product. After concentration to 150 mL the filtrate was chilled in ice, yielding more solid material. The solids were collected, redissolved in DCM, and plugged (50-100% EtOAc/DCM to remove Mitsonobu by-products then 10% MeOH/DCM to elute the desired product. After concentrating the relevant fraction to a white solid, this material was recrystallized from DCM/ether/heptane, filtered, washed with heptane, and dried overnight to give ii as a white solid (17.09 g, 64%). 1H NMR (400 MHz) δ 9.41 (s, 2H); 8.83 (d, J=4.4 Hz, 1H); 8.53 (d, J=8 Hz, 1H); 8.43 (d, J=1.2 Hz, 1H); 8.21 (d, J=1.2 Hz, 1H); 8.01 (dt, J=8, 1.6 Hz, 1H); 7.46 (dd, J=7.2, 4.8 Hz); 5.43 (m, 1H); 5.16 (s, 2H); 4.38 (s, 2H); 3.39 (q, J=7.2 Hz, 2H); 3.32 (br s, 2H); 2.55 (s, 3H); 1.64 (d, J=6.8 Hz, 3H); 1.38 (s, 9H); 1.36 (s, 9H); 1.14 (t, J=7.2 Hz). MS: 667.78 (M+H)+. Chiral HPLC: Column. Chirapak IC, 0.46 cm×25 cm; 25 min isocratic gradent 100% MeOH retention time=17.12 min.

Provenance & Evidence