Synthesis
Example 3: General procedure for the synthesis of 3-(2-fluoro-4-(trifluoromethyl)phenyl)acrylic acid from malonic acid and 2-fluoro-4-(trifluoromethyl)benzaldehyde. A mixture of 5.0 g (26.0 mmol) of 2-fluoro-4-(trifluoromethyl)benzaldehyde, 3.10 g (29.8 mmol) of malonic acid, 0.26 g (3.0 mmol) of piperidine, and 15 ml of pyridine was heated to reflux temperature until the release of carbon dioxide ceased (about 3 hours). After completion of the reaction, it was cooled to room temperature and the reaction mixture was poured into a mixture of 300 g of ice and 100 ml of 6N HCl. The precipitate was separated, washed twice sequentially with water and n-heptane and dried. 5.2 g (85% yield) of 3-(2-fluoro-4-(trifluoromethyl)phenyl)acrylic acid was obtained.1H-NMR (400MHz, D6-DMSO): δ= 6.73 (d, J = 16.1Hz, 1H, 2-H), 7.63 (d, 1H, 5'-H), 7.65 (d, J = 16.1Hz, 1H, 3-H), 7.76 (d , 1H, 3'-H), 8.07 (dd, 1H, 6'-H), 12.8 (br, 1H, COOH).
References
[1] Patent: US2005/38091, 2005, A1. Location in patent: Page column 6
[2] Patent: US2005/267179, 2005, A1. Location in patent: Page/Page column 15; 16
[3] Patent: WO2008/26149, 2008, A1. Location in patent: Page/Page column 22-23
