Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.
Procedure: To an oven-dried flask was added potassium ethyl malonate (3.66 g, 21.5 mmol) and freshly distilled acetonitrile (70 mL). The mixture was cooled to 10° C. to 15° C. and stirred under an atmosphere of nitrogen and to it added anhydrous magnesium chloride (2.44 g, 25.7 mmol) and triethylamine (2.05 g, 20.3 mmol). The mixture was then stirred at room temperature under nitrogen for 2.5 hours. The resultant white slurry was recooled to 0° C. and 2,4,5-trifluorobenzoyl chloride was added over a period of 15 minutes, followed by more triethylamine (0.23 g, 2.3 mmol). The mixture was then stirred at room temperature overnight under nitrogen. Acetonitrile was then removed in vacuo and toluene (30 mL) was added. The mixture was reconcentrated and more toluene (60 mL) then added. Hydrochloric acid (1.5 M, 40 mL) was cautiously added, ensuring that the temperature did not exceed 25° C., and the aqueous layer separated. The organic fraction was washed with 1.5 M HCl (2×25 mL) and water (2×25 mL), dried over MgSO4, and solvent removed in vacuo to afford 3-oxo-3-(2,4,5-trifluoro-phenyl-propionic acid ethyl ester as a pale orange solid (2.35 g, 9.55 mmol, 94%). Rf 0.55 (CH2C2), mp 57-59° C. FTIR, νmax/cm −1 3088, 2990, 1735, 1687, 1514, 1429, 1321, 1205, 1140, 1055, 897, 807. 1 H NMR (CDCl3, 250 MHz), δ/ppm [12.69 (s), 5.81 (s) and 3.92 (d, J=3.9 Hz)] (2 H, keto-enol tautomers); 7.74 (1 H, m, Ar H); 6.98 (1 H, m, Ar H); 4.24 and 4.17 (2 H, both q, 3J=7.1 Hz); 1.31 and 1.24 (3 H, both t, 3J=7.1 Hz). 13C{1 H}NMR (CDCl3, 63 MHz), δ/ppm 187.8 (C=O); 173.0 (—HC=C); 166.9 (CO2Et); 163.7, 159.8, 155.9, 151.8, 149.0, 145.3, 120.9 (quat. Ar C); 118.7, 106.6 (Ar C—H); 92.9 (HC=C); 61.4 and 60.6 (—OCH2); 49.4 (—OCCH2CO—); 14.0 (—CH3). 19FNMR (CDCl3, 235 MHz) δ/ppm −110.6 and −111.7 (m, Ar F); −123.5 and −129.0 (m, Ar F); −140.5 and −141.7 (m, Ar F). λmax/nm (δ/dm3mol−1cm−1) 295 (4781), 281 (3962), 240 (5191). HRMS (EI), M+/z C11H9F3O3 (M−) requires 246.0504; found 246.0514.
The mixture was cooled to 10° C. to 15° C.
The mixture was then stirred at room temperature under nitrogen for 2.5 hours
was recooled to 0° C.
The mixture was then stirred at room temperature overnight under nitrogen
Acetonitrile was then removed in vacuo and toluene (30 mL)
was added
more toluene (60 mL) then added
Hydrochloric acid (1.5 M, 40 mL) was cautiously added
did not exceed 25° C.
the aqueous layer separated
The organic fraction was washed with 1.5 M HCl (2×25 mL) and water (2×25 mL)
dried over MgSO4, and solvent
removed in vacuo
Source ID: ord-b791fa9f0a104f8db9993dc257a5b7fc