To a DMF (150 mL) solution of 5-(4′-bromomethyl-biphenyl-2-yl)-1-trityl-1H-tetrazole (30 g, 53.8 mmol) was added 2-butyl-5-chloro-3H-imidazole-4-carbaldehyde (10 g, 53.8 mmol) and K2CO3 (7.4 g, 53.8 mmol). The mixture was stirred at room temperature overnight. EtOAc (500 mL) was added and the organic was washed three times with a NaHCO3 solution (200 mL) followed by saturated aqueous NaCl (200 mL). Solvent was removed and purification was achieved by silica gel chromatography (50:50 EtOAc:hexanes) using an isocratic gradient to provide intermediate (11a) a white solid (41 g). MS m/z: [M+H+] calcd for C41H35ClN6O, 663.26. found 663.4. 1H-NMR (d4-MeOH): 0.83 (m, 3H), 1.26 (m, 2H), 1.53 (m, 2H), 2.53 (m, 2H), 5.56 (s, 2H), 6.87-6.96 (m, 8H), 7.05 (m, 2H), 7.25-7.43 (m, 10H), 7.53-7.58 (m, 2H), 7.84 (d, 1H), 9.73 (s, 1H).
