mCPBA (77%, 2.07 g, 9.24 mmol) and NaHCO3 (0.78 g, 9.24 mmol) was added to a solution of 1-{[(α-benzoylbenzyloxy)carbonyl]aminomethyl}-1-cyclohexane acetic acid (15) (1.89 g, 4.62 mmol) in 40 mL of CH2Cl2 at room temperature and the resulting mixture was stirred at room temperature overnight. The reaction mixture was acidified with citric acid, extracted with CH2Cl2 and the organic phase was washed with brine, dried over Na2SO4 and concentrated under reduced pressure. The residue was purified by reverse phase preparative HPLC to afford 960 mg (49%) of the title compound.
