Reaction Steps
A 100 mL round-bottom flask was charged with triphosgene (121 mg, 0.410 mmol, 0.70 equiv), dichloromethane (15 mL), 1,1,1,3,3,3-hexafluoropropan-2-ol (196 mg, 1.17 mmol, 2.00 equiv) and N-ethyl-N-isopropylpropan-2-amine (301 mg, 2.33 mmol, 4.00 equiv) were added at 0° C. The mixture was stirred for 2 h at room temperature. 4-(4-[[(3R)-3-Methylpiperazin-1-yl]methyl]-3-(trifluoromethyl)phenyl) morpholine (200 mg, 0.580 mmol, 1.00 equiv) and 4-dimethylaminopyridine (71.0 mg, 0.580 mmol, 1.00 equiv) were added. The resulting solution was stirred overnight at room temperature, diluted with H2O (10 mL), extracted with dichloromethane (3×10 mL). The organic layers were combined and washed with brine (50 mL), dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product (500 mg) was purified by preparative HPLC using the following gradient conditions: 20% CH3CN/80% Phase A increasing to 80% CH3CN over 10 min, then to 100% CH3CN over 0.1 min, holding at 100% CH3CN for 1.9 min, then reducing to 20% CH3CN over 0.1 min, and holding at 20% for 1.9 min, on a Waters 2767-5 Chromatograph. Column: Xbridge Prep C18, 19*150 mm 5 um; Mobile phase: Phase A: aqueous NH4HCO3 (0.05%); Phase B: CH3CN; Detector, UV220 & 254 nm. Purification resulted in 229 mg (73% yield) of 1,1,1,3,3,3-hexafluoropropan-2-yl(2R)-2-methyl-4-[[4-(morpholin-4-yl)-2-(trifluoromethyl)phenyl]methyl]piperazine-1-carboxylate as yellow oil. 1H NMR 300 MHz (CDCl3) δ 7.57 (d, J=8.7 Hz, 1H), 7.13 (s, 1H), 7.01-7.05 (m, 1H), 5.71-5.83 (m, 1H), 4.26 (br, 1H), 3.87 (t, J=4.8 Hz, 5H), 3.55 (s, 2H), 3.26-3.30 (m, 1H), 3.20 (t, J=4.8 Hz, 4H), 2.79 (d, J=10.8 Hz, 1H), 2.63 (d, J=11.4 Hz, 1H), 2.25-2.33 (m, 1H), 2.07-2.16 (m, 1H), 1.30 (d, J=6.6 Hz, 3H). LCMS (ESI, m/z): 538 [M+H]+.
