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With caesium carbonate; In 1-methyl-pyrrolidin-2-one; at 100℃; for 0.833333h; |
General procedure: Example 1 Preparation of 5-(2-(2,4-dimethoxyphenoxy)-5-(trifluoromethyl)benzamido)picolinic acid (65) [embedded image] A solution of 2-fluoro-5-(trifluoromethyl)benzoyl chloride (2.98 mL, 19.72 mmol) in dichloromethane (22.3 mL) was added drop-wise to a mixture of methyl 5-aminopyridine-2-carboxylate (3.0 g, 19.72 mmol), pyridine (4.80 mL, 59.16 mmol) and dichloromethane (89.4 mL) at 0 C. The mixture was removed from the ice bath after 1.5 hours and was stirred at room temperature for 0.5 hours. The mixture was poured into 1N HCl (50 mL) and dichloromethane (50 mL). The layers were separated and the organic layer was dried over sodium sulfate, filtered and concentrated under reduced pressure. The product was slurried in hexanes to remove impurities. The solid was isolated by filtration rinsing with hexanes to yield methyl 5-[[2-fluoro-5-(trifluoromethyl)benzoyl]amino]pyridine-2-carboxylate (5.16 g, 76%) as an off-white solid. 1H NMR (400 MHz, DMSO-d6) - 11.18 (s, 1H), 8.95 (d, J=2.5 Hz, 1H), 8.38 (dd, J=8.6, 2.5 Hz, 1H), 8.16 (dd, J=6.1, 2.4 Hz, 1H), 8.13 (d, J=8.6 Hz, 1H), 8.09-7.98 (m, 1H), 7.67 (t, J=9.2 Hz, 1H), 3.88 (s, 3H) ppm. ESI-MS m/z calc. 342.06. found 343.2 (M+1)+. Retention time: 1.54 minutes (3 minutes run).To 5-[[2-fluoro-5-(trifluoromethyl)benzoyl]amino]pyridine-2-carboxylate (51.3 mg, 0.15 mmol) in N-methylpyrrolidinone (1 mL) was added 2,4-dimethoxyphenol (23.1 mg, 0.45 mmol), cesium carbonate (146.6 mg, 0.45 mmol) and the mixture was heated at 100 C. for 50 minutes to yield methyl 5-(2-(2,4-dimethoxyphenoxy)-5-(trifluoromethyl)benzamido)picolinate that was taken into the next step without further purification.Sodium hydroxide (150 -L, 3M) and methanol (150 -L) were added to the methyl 5-(2-(2,4-dimethoxyphenoxy)-5-(trifluoromethyl)benzamido)picolinate prepared in the previous step, and the reaction was stirred at 50 C. from 3 hours. The reaction mixture was filtered and purified by reverse phase preparative chromatography utilizing a gradient of 10-99% acetonitrile in water containing HCl as a modifier to yield 5-(2-(2,4-dimethoxyphenoxy)-5-(trifluoromethyl)benzamido)picolinic acid hydrochloric acid (65) (37.3 mg, 49%). 1H NMR (400 MHz, DMSO-d6) - 10.97 (s, 1H), 8.97 (d, J=2.5 Hz, 1H), 8.35 (dd, J=8.8, 2.5 Hz, 1H), 8.09 (d, J=8.6 Hz, 1H), 8.00 (d, J=2.3 Hz, 1H), 7.78 (dd, J=8.9, 2.4 Hz, 1H), 7.24 (d, J=8.8 Hz, 1H), 6.92-6.69 (m, 2H), 6.61 (dd, J=8.8, 2.8 Hz, 1H), 3.79 (s, 3H), 3.73 (s, 3H) ppm. ESI-MS m/z calc. 462.10. found 463.5 (M+1)+. Retention time: 1.81 minutes (3 minutes run). The following compounds were prepared using a procedure similar to the one described above for compound 65 from the following alcohols. |