Reaction Steps
3-(2-Methoxycarbonylamino-3-methyl-butyryl)-imidazolidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-methyl ester (460 mg, 1.18 mmol) was dissolved in THF (3 mL) and MeOH (2 mL). An aqueous solution of LiOH (49.8 mg, 1.18 mmol) was added and stirring at room temperature was continued. After the hydrolysis was complete, the reaction was neutralized with aqueous HCl (1.18 mL, 1M). The organic solvents were removed in vacuo and the aqueous suspension was frozen and lyophilized. The crude material was used in the next step without further purification. The crude material was dissolved in DMF (4.0 mL) and HATU (448 mg, 1.18 mmol) and DIEA (152 mg, 1.18 mmol) were added. The reaction was stirred at room temperature for five minutes, after which the amino-(4′bromo) acetophenone hydrochloride salt (295 mg, 1.18 mmol) was added. Stirring at room temperature was continued. After 90 minutes, all volatiles were removed in vacuo and the crude material was purified via silica gel chromatography (eluent: EtOAc/hexanes) to yield the slightly impure product 442-(4-Bromo-phenyl)-2-oxo-ethylcarbamoyl]-3-(2-methoxycarbonylamino-3-methyl-butyryl)-imidazolidine-1-carboxylic acid tert-butyl ester (723 mg): LCMS-ESI+: calc'd for C24H33BrN4O7: 569.4 (M+). Found: 570.4/572.4 (M+H+). 4-(4-Bromo-phenyl)-3′-(2-methoxycarbonylamino-3-methyl-butyryl)-2′,3′,4′,5′-tetrahydro-1H-[2,4′]biimidazolyl-1′-carboxylic acid tert-butyl ester: 4-[2-(4-Bromo-phenyl)-2-oxo-ethylcarbamoyl]-3-(2-methoxycarbonylamino-3-methyl-butyryl)-imidazolidine-1-carboxylic acid tert-butyl ester (723 mg) was dissolved in m-xylenes (6.0 mL) and heated at 135° C. Solid ammonium acetate (500 mg, 6.48 mmol) was added and the reaction was stirred at 135° C. After 45 minutes, the reaction was cooled to room temperature and the volatiles were removed in vacuo. The crude material was purified via silica gel chromatography (eluent: EtOAc w 10% MeOH/hexanes) to yield the product 4-(4-Bromo-phenyl)-3′-(2-methoxycarbonylamino-3-methyl-butyryl)-2′,3′,4′,5′-tetrahydro-1H-[2,4]biimidazolyl-1′-carboxylic acid tert-butyl ester (436 mg): LCMS-ESI+: calc'd for C24H32BrN5O5: 550.4 (M+). Found: 551.2/553.2 (M+H+). 3′-(2-Methoxycarbonylamino-3-methyl-butyryl)-5-(4′-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-biphenyl-4-yl)-2′,3′,4′,5′-tetrahydro-1H-[2,4]biimidazolyl-1′-carboxylic acid tert-butyl ester: 4-(4-Bromo-phenyl)-3′-(2-methoxycarbonylamino-3-methyl-butyryl)-2′,3′,4′,5′-tetrahydro-1H-[2,4]biimidazolyl-1′-carboxylic acid tert-butyl ester (75 mg, 0.136 mmol) was combined with [2-Methyl-1-(2-{4-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-propyl]-carbamic acid methyl ester (67.6 mg, 0.136 mmol) under an argon atmosphere. Potassium carbonate (37.5 mg, 0.272 mmol) and Pd(PPh3)4 (15.7 mg, 0.014 mmol) were added, followed by DME (3 mL) and water (0.6 mL). The mixture was heated under microwave conditions for 20 minutes at 120° C. All volatiles were removed in vacuo and the crude material was dissolved in DMF and purified via RP-HPLC (eluent: water/MeCN w 0.1% TFA) to yield the product (55 mg): LCMS-ESI+: calc'd for C44H57N9O8: 839.9 (M+). Found: 840.5 (M+H+); 1H-NMR: 300 MHz, (MeOH-d4) δ: 7.90-7.81 (m, 10H), 5.58 (m, 1H), 5.43 (m, 1H), 5.25-5.20 (m, 2H), 4.24 (d, J=7.5 Hz, 1H), 4.11 (m, 1H), 3.99 (m, 1H), 3.86 (m, 2H), 3.67 (s, 3H), 3.66 (s, 3H), 3.46 (d, J=7.2 Hz, 1H), 2.59 (m, 1H), 2.22-2.10 (m, 5H), 1.53 & 1.44 (s, 9H) 1.04-0.89 (m, 12H).
