5-iso-Butyl-2-(N-tert-butylaminosulfonyl)thiophene-3-boronic acid (200.5 mg, 0.628 mmol, see step (c) above), 1-(4-bromobenzyl)-1H-imidazole (98.8 mg, 0.416 mmol, see step (d) above), toluene (15 mL), ethanol (15 mL), NaOH (1.0M, 1.5 mL, 1.5 mmol) and Pd(PPh3)4 (14.5 mg, 0.125 mmol) were mixed under N2. The mixture was warmed to reflux for 2 h. The mixture was diluted with EtOAc (50 mL), washed with water and brine, and dried over MgSO4. The solvent was removed and the residue was separated by column chromatography with chloroform:methanol (20:1) as an eluent to give 113.9 mg of the sub-title compound (yield: 63.27%).
