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)C12-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%). 2-[5-(4-Chloro-2-cyano-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester: 245-(4-Chloro-2-formyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (985 mg, 2.62 mmol) was dissolved in ethanol (20 mL) and hydroxylamine (50% w/w in H2O, 642 μL, 10.48 mmol) was added. After stirring at room temperature for 15 h, the solution was concentrated. To the crude oxime was added TBSCl (474 mg, 3.14 mmol), imidazole (357 mg, 5.24 mmol) and DMF (10 mL). The reaction mixture was stirred at 120° C. for 80 minutes at which point more TBSCl (237 mg, 1.58 mmol) and imidazole (177 mg, 2.60 mmol) were added. The reaction mixture was stirred an additional 17 hours at 120° C. then cooled to room temperature, diluted with EtOAc. The organic phase was washed with saturated aqueous NaHCO3 and brine then dried over MgSO4, filtered and concentrated under reduced pressure. The crude residue was purified by silica column chromatography (25% to 50% EtOAc/Hexane) to afford the title compound 2-[5-(4-Chloro-2-cyano-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (500 mg, 51%). (1-{2-[5-(4-Chloro-2-cyano-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester: Title compound was prepared according to the method employed to prepare {1-[2-(4′-Chloro-biphenyl-3-ylcarbamoyl)-pyrrolidine-1-carbonyl]-2-methyl-propyl}-carbamic acid methyl ester (Example CX), substituting 2-[5-(4-Chloro-2-cyano-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester for 2-(4′-Chloro-biphenyl-3-ylcarbamoyl)-pyrrolidine-1-carboxylic acid tert-butyl ester. 3-Cyano-4-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenylboronic acid: Title compound was prepared according to the method employed to prepare 2-{5-[2′-Cyano-4′-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-biphenyl-4-yl]-1H-imidazol-2-yl}-pyrrolidine-1-carboxylic acid tert-butyl ester (Example CZ), substituting (1-{2-[5-(4-Chloro-2-cyano-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester for 245-(4′-Chloro-2′-cyano-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester. (1-{2-[5-(3-Cyano-4′-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester: Title compound was prepared according to the method employed to prepare [1-(2-{5-[6-(4-{2-[1-(2-Methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenyl)-naphthalen-2-yl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-2-methyl-propyl]-carbamic acid methyl ester (Example AZ), substituting 3-Cyano-4-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenylboronic acid for [2-methyl-1-(2-{5-[6-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-naphthalen-2-yl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-propyl]-carbamic acid methyl ester. 1H-NMR: 400 MHz, (DMSO-d6) δ 12.13 (s, 1H), 8.13-8.04 (m, 2H), 7.85-7.75 (m, 4H), 7.57 (s, 1H), 7.31 (dd, J=3.6 Hz, 8.4 Hz, 1H), 5.13-5.10 (m, 2H); MS (ESI) m/z 764 [M+H]+.

Provenance & Evidence