Cesium fluoride → 1-(5-Bromothiophen-2-yl)-2,2,2-trifluoroethanol

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Reaction Steps

CsF (400 mg, 2.6 mmol) was added to a solution of 5-bromothiophene-2-carboxaldehyde (5.0 g, 26.17 mmol) in dry 1,2-dimethoxyethane (20 mL), followed by trifluoromethyl trimethylsilane (4.6 mL, 31.4 mmol) dropwise at 0° C. The reaction mixture was stirred at room temperature for 3 h, quenched with 1.5N HCl, and stirred for an additional 30 min. The crude product was extracted with CH2Cl2. The combined extracts were dried over anhydrous Na2SO4, and concentrated under reduced pressure. The crude product was purified by column chromatography (silica 60-120 mesh, eluant 5-10% EtOAc in petroleum ether) to get 1-(5-bromothiophen-2-yl)-2,2,2-trifluoroethanol (4 g, yield 59%). 1H NMR (400 MHz, CDCl3) δ 7.01 (m, 1H), 6.95 (m, 1H), 5.23-5.18 (q, J=5.9 Hz, 1H), 3.07 (br s, 1H). MS (ESI) m/z: Calculated for C6H4BrF3OS: 261.91. found: 260.7 (M−1)−

Provenance & Evidence