4-Chloro-2-formylphenylboronic Acid (contains varying amounts of Anhydride) → 2-[5-(4-Chloro-2-formyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

2-(5-Bromo-1H-imidazol-2-yl)-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g, 6.32 mmol), 4-Chloro-2-formyl-phenylboronic acid (1.17 g, 6.32 mmol), Pd(PPh3)4 (365 mg, 0.316 mmol), Pd(dppf)Cl2-DCM (258 mg, 0.316 mmol) K2CO3 (2 M, 6.3 mL, 12.6 mmol) and DME (30 mL) were combined in a round bottom flask. The stirred suspension was degassed for 10 minutes with bubbling N2 then heated to 85° C. After 4 h, the reaction mixture was poured into saturated aqueous NaHCO3. The aqueous phase was extracted 3× with EtOAc and the combined organics were dried over MgSO4, filtered and concentrated under reduced pressure. The crude residue was purified by silica column chromatography (25% to 75% EtOAc/Hexane) to afford the title compound 2-[5-(4-Chloro-2-formyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.85 g, 78%).

Provenance & Evidence