1,1,1,3,3,3-Hexafluoro-2-propanol → 1,1,1,3,3,3-Hexafluoropropan-2-yl 4-[[2-(morpholin-4-yl)-4-(trifluoromethyl)phenyl]methyl]piperazine-1-carboxylate

Participants

Reaction Steps

A 50 mL round-bottom flask was charged with 1,1,1,3,3,3-hexafluoropropan-2-ol (168 mg, 1.00 mmol, 1.10 equiv), triphosgene (99.0 mg, 0.330 mmol, 0.33 equiv), dichloromethane (10 mL). N,N-Diisopropylethylamine (381 mg, 2.95 mmol, 3.24 equiv) was added dropwise. The mixture was stirred at room temperature for 2 h. 4-[2-(Piperazin-1-ylmethyl)-5-(trifluoromethyl)phenyl]morpholine (300 mg, 0.910 mmol, 1.00 equiv) was added. The resulting solution was stirred for 2 hours at room temperature and diluted with dichloromethane (20 mL). The resulting mixture was washed with H2O (2×10 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was chromatographed on a silica gel column with ethyl acetate/petroleum ether (1/3). The crude product (337 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% over 0.1 min, and holding at 20% for 1.9 min, on a waters 2767-5 chromatograph. Column: X-bridge 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 171.9 mg (35% yield) of 1,1,1,3,3,3-hexafluoropropan-2-yl 4-[[2-(morpholin-4-yl)-4-(trifluoromethyl)phenyl]methyl]piperazine-1-carboxylate as light yellow oil. 1H NMR 300 MHz (CDCl3) δ 7.54-7.623 (m, 1H), 7.33-7.42 (m, 2H), 5.72-5.85 (m, 1H), 3.84-3.87 (m, 4H), 3.64 (s, 2H), 3.56-3.57 (m, 4H), 2.96-3.00 (m, 4H), 2.51-2.52 (m, 4H). LCMS (ESI, m/z): 524 [M+H]+.

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