Potassium Carbonate → 1-tert-butyl 2-methyl 3-phenyl-1H-pyrrole-1,2-dicarboxylate

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To a solution of 1-tert-butyl 2-methyl 3-bromo-1H-pyrrole-1,2-dicarboxylate (17.6 g, 57.9 mmol) in toluene (200 mL) and water (200 mL) was added potassium carbonate (64.0 g, 463 mmol), followed by phenylboronic acid (10.6 g, 87.0 mmol) and tetrabutylammonium bromide (1.68 g, 5.21 mmol). The reaction mixture degassed for 10 min with nitrogen and then tetrakis(triphenylphosphine)palladium (1.34 g, 1.16 mmol) was added. The resulting slurry was degassed with nitrogen for 30 min and then heated to reflux for 16 h. The reaction mixture was concentrated under reduced pressure to remove water and toluene. Water was then added to the residue and the mixture extracted by ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by column chromatography using CombiFlash (REDISEP®, silica gel, 80 g, 20% EtOAc/hexanes) to obtain 1-tert-butyl 2-methyl 3-phenyl-1H-pyrrole-1,2-dicarboxylate (11.5 g, 65.9%) as a tan solid. 1H NMR (400 MHz, CD3OD) δ ppm: 1.60 (s, 9H), 3.79 (s, 3H), 6.40 (d, J=3.4 Hz, 1H), 7.37 (m, 6H).

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