To a solution of 4-bromo-2-nitrobenzaldehyde (20.2 g, 87.9 mmol), 4-(pyrrolidine-1-carbonyl)phenylboronic acid (21.2 g, 96.7 mmol), and Pd(PPh3)4 (508 mg, 0.440 mmol) in toluene (200 mL) was added EtOH (40 mL) followed by Na2CO3 (70.0 mL, 140 mmol, 2 M aq solution) at room temperature. The resulting mixture was heated at 100° C. for 18 h. The reaction mixture was cooled to room temperature and the organic layer was separated. The aqueous layer was extracted with EtOAc (300 mL). The combined organic layers were washed with brine (500 mL), dried over MgSO4, filtered, and concentrated under reduced pressure to give the crude material that was combined with another batch of the crude material obtained from an additional run in the same reaction scale. The combined crude material was purified by silica gel flash column chromatography (CH2Cl2 to 1% MeOH in CH2Cl2) to afford 51 g (90%) of 3-nitro-4′-(pyrrolidine-1-carbonyl)biphenyl-4-carbaldehyde.
