2-Thiophenemethanol, a-(trifluoromethyl)- synthesis
- Product Name:2-Thiophenemethanol, a-(trifluoromethyl)-
- CAS Number:35304-68-8
- Molecular formula:C6H5F3OS
- Molecular Weight:182.16
98-03-3
81290-20-2
35304-68-8
(Trifluoromethyl)trimethylsilane (28.4 g, 0.2 mol) was slowly added dropwise to a suspension of 2-thiophenecarboxaldehyde (11.2 g, 0.1 mol) and cesium fluoride (1.52 g, 0.01 mol) in 1,2-dimethoxyethane (70 mL) at 0 °C. The reaction mixture was warmed to 25 °C and stirred for 3 h until the feedstock was completely consumed. Subsequently, the reaction was quenched by the addition of 3N hydrochloric acid solution and stirring was continued for 0.5 h to ensure complete conversion of the intermediate to the target product 2,2,2-trifluoro-1-(thiophen-2-yl)ethanol. The reaction mixture was extracted with ethyl acetate and the organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (200 g silica gel, petroleum ether/ethyl acetate = 1% to 2% gradient elution) to afford the oily target product 125b (17.2 g, 97% yield).1H NMR (CDCl3) data were as follows: δ 7.39-7.38 (m, 1H), 7.19-7.18 (d, 1H, J=3.6 Hz), 7.05- 7.03 (m, 1H), 5.29-5.23 (m, 1H).
Yield:35304-68-8 97%
Reaction Conditions:
Stage #1: thiophene-2-carbaldehyde;(trifluoromethyl)trimethylsilanewith cesium fluoride in 1,2-dimethoxyethane at 0 - 25;
Stage #2: with hydrogenchloride in 1,2-dimethoxyethane;water; for 0.5 h;
Steps:
57.1 Step 1
To a suspension of 125a (11.2 g, 0.1 mol) and CsF (1.52 g, 0.01 mol) in DME (70 mL) was added TMSCF3 (28.4 g, 0.2 mol) dropwise at 0 °C. Then the mixture was stirred at 25°C for 3 hours. The starting material was consumed up. After that, HC1 (3N) was added to quench the reaction and it was stirred for another 0.5 hours. The intermediate was used up and the desired product was formed. Extracted with ethyl acetate, dried over anhydrous sodium sulfate, concentrated in vacuo and purified using Si02 chromatography (200 g, Petroleum Ether/EtOAc = 1% to 2%) to providel25b as a oil (17.2 g, 97% yield). 1H NMR (CDC13): 7.39 - 7.38 (m, 1 H) , 7.19 - 7.18 d, 1 H, J=3.6Hz), 7.05 - 7.03 (m, 1 H), 5.29 - 5.23 (m, 1 H)
References:
WO2014/110688,2014,A1 Location in patent:Page/Page column 154
