(1-{2-[5-(4-Bromo-phenyl)-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (1033 mg, 1.8 mmol) and 4-Cbz-piperazine (588 mg, 2.7 mmol) in toluene (9 mL) were treated with Pd(OAc)2 (20 mg, 0.09 mmol), BINAP (110 mg, 0.1 mmol), and NaOtBu (428 mg, 4.45 mmol). The mixture was stirred in a sealed tube at 110° C. for 18 hours. The solution was concentrated, diluted with EtOAc (50 mL), and washed with saturated NaHCO3 (20 mL), H2O (20 mL), and brine (20 mL). The solution was dried over MgSO4 and subjected to a 120 g SiO2 COMBIFLASH column (0-100% EtOAc-hexanes gradient) to afford 4-{-4-[2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3-(2-trimethylsilanyl-ethoxymethyl)-3H-imidazol-4-yl]-phenyl}-piperazine-1-carboxylic acid benzyl ester (166 mg, 13%): MS (ESI) m/z 719 [M+H]+.
