SYNTHESIS OF 3,3,3-TRIFLUOROPROPIONIC AND 4,4,4-TRIFLUORO-2-KETOBUTYRIC ACIDS

Article abstract of DOI:10.1016/S0022-1139(00)81235-X

Trifluoroethyl cyclohexyl ketone (4) is prepared by acylation of difluoroethylene (2) with cyclohexanecarboxylic acid chloride (1), followed by Cl->F exchange with potassium fluoride in the presence of triethylbenzylammonium chloride.Bayer-Villinger oxidation of ketone (4) with trifluoroperacetic acid gives cyclohexyl trifluoropropionate (5). 3,3,3-trifluoropropionic acid (6) is obtained by treatment of (5) with trimethylsilyl iodide.Condensation of 2,2,2-trifluorodiazoethane (7) with ethyl glyoxylate (8) gives mainly ethyl 4,4,4-trifluoro-2-ketobutyric acid ester (9) which leads after hydrolysis to the corresponding acid (12).