A solution of 3-((R)-2-cyclohexyl-6-oxo-piperazin-1-yl)-5-phenyl-thiophene-2-carboxylic acid (50.0 mg, 0.13 mmol, 1.0 equiv) and 3-fluoro-2-morpholinobenzaldehyde (108.8 mg, 0.52 mmol, 4.0 equiv) in acetic acid (0.2 mL) and methanol (0.5 mL) was stirred at room temperature for 60 minutes. Then sodium triacetoxyborohydride (110.2 mg, 0.52 mmol, 4.0 equiv) was added to the mixture and the resulting mixture was stirred at 75° C. for 3 hours. The solvent was removed by Genevac and the residue was dissolved in EtOAc (6 mL). The organic phase was washed by brine (3 mL), dried over Na2SO4 and concentrated. The residue was purified by HPLC (0.1% NH4OH) to afford the product (9 mg, 12%). MS: 577.2 [M−H+].
