(3Z) -1,1,1- trifluoro-4-methoxy-4- (2-methylphenyl) but-3-en-2-one
[Step 1]
1- (1,1-dimethoxy-ethyl) -2-methyl-benzene
2 methylacetophenone 5.36g (40mmol), trimethyl orthoformate 5.0g (47mmol), methanol - Le 7.7g (240mmol), and methane sulfonic in toluene solution (100mL) containing sodium sulfate 14.2g (100mmol) and adding an acid 92mg (0.8mmol) was stirred at room temperature for 20 hours. The reaction mixture was diluted with ethyl acetate, washed with a saturated aqueous sodium bicarbonate solution, and dried over magnesium sulfate and concentrated. The crude product was basic silica gel column and purified by (0-10% ethyl acetate / hexanes) to give the title compound 5.5g (76%) I was obtained as a colorless oil. 1 H-NMR (400MHz, CDCl 3) δ: 1.56 (3H, s), 2.46 (3H, s), 3.19 (6H, s), 7.09-7.24 (3H, m ), 7.60-7.68 (1H, m).
[Step 2]
(3Z) -1,1,1- trifluoro-4-methoxy-4- (2-methylphenyl) but-3-en-2-one
Reference Examples were synthesized in Step 1 of 8 1- (1,1-dimethoxy-ethyl) -2-methylbenzene 900mg (5mmol), pyridine 790mg of (10mmol) was dissolved in THF (15mL), 0 ℃ to the cooled trifluoroacetic anhydride fluoro acetate 2.1g the (10mmol) we were slowly dropping. After stirring at room temperature for 18 hours, the reaction mixture was washed with 0.1N aqueous hydrochloric acid and diluted with ethyl acetate. The crude product and the organic layer was obtained by drying your concentrated magnesium sulfate and purified by silica gel chromatography (0-10% ethyl acetate / hexanes) to give the title compound 1.0g (82%) was obtained as a colorless oil. 1 H-NMR (400MHz, CDCl 3) δ: 2.22 (3H, s), 3.94 (3H, s), 5.96 (1H, s), 7.11-7.18 (1H, m ), 7.20-7.30 (2H, m), 7.33-7.40 (1H, m). LC-MS, 245 (M + 1).
References
1
http://www.google.fr/patents/WO2010110400A1?cl=en&hl=fr
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