Synthesis
General procedure for the synthesis of diethyl 2,2-difluoroglutarate from ethyl bromodifluoroacetate and ethyl acrylate: copper powder (700 mg) and tetrahydrofuran (5.8 mL) were added to the reaction vessel and stirred at 50 °C. Ethyl acrylate (0.50 g), ethyl bromodifluoroacetate (2.53 g), TMEDA (0.29 g) and acetic acid (0.27 g) were then added sequentially. The reaction was terminated after 0.5 hrs. To the reaction mixture was added 10% aqueous ammonium chloride solution, filtered through a diatomaceous earth pad to remove the copper residue, and the filtrate was extracted with methyl tert-butyl ether to afford diethyl 2,2-difluoroglutarate (1.09 g, 97.4% yield). Alternatively, diethyl 2,2-difluoroglutarate (1.08 g, 96.4% yield) was obtained by following the same method as described above except that water (0.10 g) was used instead of acetic acid.
References
[1] Patent: CN104159884, 2016, B. Location in patent: Paragraph 0060; 0061; 0062; 0063; 0064
[2] Synthesis, 2012, vol. 44, # 20, p. 3165 - 3170,6
[3] Patent: WO2009/82134, 2009, A2. Location in patent: Page/Page column 41-42
[4] Patent: WO2012/30106, 2012, A2. Location in patent: Page/Page column 11
[5] Patent: US2013/165659, 2013, A1. Location in patent: Paragraph 0098; 0099; 0100
