2-{5-[4-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carboxylic acid tert-butyl ester (2 g, 4.55 mmol), 2-Bromo-5-chloro-benzonitrile (985 mg, 4.55 mmol), Pd(PPh3)4 (263 mg, 0.228 mmol) and a 2 M aqueous solution of potassium carbonate (4.6 mL, 9.2 mmol) were suspended in 1,2-methoxyethane (20 mL) and degassed for 10 min. The stirred reaction mixture was heated to 85° C. for 21 hours then poured into a saturated aqueous solution of NaHCO3 (250 mL). The aqueous phase was extracted 3 times with ethyl acetate and the combined organic layers were dried over magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (65% to 90% EtOAc/hexanes) to afford 2-[5-(4′-Chloro-2′-cyano-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.65 g, 81%). 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: 2-[5-(4′-Chloro-2′-cyano-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.68 g, 3.74 mmol), bis(pinacolato)diboron (1.43 g, 5.61 mmol), Pd2(dba)3 (86 mg, 0.0935 mmol), x-phos (214 mg, 0.449 mmol) and potassium acetate (1.10 g, 11.22 mmol) were suspended in dioxane (20 mL) and degassed for 10 min with nitrogen. The stirred reaction mixture was heated to 90° C. for 15 h, then cooled and filtered over a bed of silica, eluting with ethyl acetate until all desired product was removed. The liquid was concentrated and the resulting residue was purified by silica column chromatography (55% to 80% EtOAc/hexanes) to afford 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 (1.57 g, 78%). (1-{2-[5-(2′-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: 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 (1.60 g, 2.96 mmol), 2-(5-Bromo-1H-imidazol-2-yl)-pyrrolidine-1-carboxylic acid tert-butyl ester (935 mg, 2.96 mmol), Pd(PPh3)4 (171 mg, 0.148 mmol), Pd(dppf)Cl2 (121 mg, 0.148 mmol) and a 2 M aqueous solution of potassium carbonate (3 mL, 6 mmol) were suspended in 1,2-dimethoxyethane and degassed for 11 min. The stirred reaction mixture was heated to 85° C. for 100 min, then poured into a saturated aqueous solution of sodium bicarbonate (200 mL) and extracted 3 times with ethyl acetate. The combined organic layers were dried over magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (5% to 10% MeOH/DCM) to afford the Suzuki coupled product (438 mg, 23%). This material (174 mg, 0.268 mmol) was treated with 4 M HCl in dioxane (4 mL). Solubility was poor so 2 mL dichloromethane and 4 mL DMF were added. After stirring for 40 min, the mixture was concentrated. The crude residue was treated with 2-Methoxycarbonylamino-3-methyl-butyric acid (103 mg, 0.590 mmol), HATU (255 mg, 0.670 mmol) and DMF (5 mL) and cooled to 0° C. DIPEA (0.470 mL, 2.68 mmol) was added and the reaction mixture was stirred for 4 hours then poured into a saturated aqueous solution of sodium bicarbonate (200 mL) and extracted 3 times with ethyl acetate. The combined organic layers were dried over magnesium sulfate and concentrated. The crude residue was brought up in DMF and water and purified by reverse phase preparative HPLC, giving (1-{2-[5-(2′-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 (75 mg, 37%). (MeOH-d4, 400 MHz) 8.19-7.35 (m, 11H), 5.18 (m, 2H), 4.24 (m, 2H), 4.03-4.86 (m, 4H), 3.65 (s, 6H), 2.37-2.00 (m, 10H), 1.00-0.90 (m, 12H); MS (ESI) m/z 764 [M+H]+.
