m-Chloroperbenzoic acid → rac-(3aR,5S,6aS)-2-[4-(trifluoromethoxy)phenyl]hexahydro-1H-spiro[cyclopenta[c]pyrrole-5,2'-oxiran]-1-one

To a solution of 5-Methylene-2-(4-trifluoromethoxy-phenyl)-hexahydro-cyclopenta[c]pyrrol-1-one (0.78 g, 2.6 mmol) in dichloromethane (20 mL) was added mCPBA (0.9 g, 5.2 mmol) at 0° C., and the mixture was stirred for 6 h at room temperature. Saturated solution of NaHCO3 (30 mL) was added and stirred for another 0.5 h. The mixture was extracted with dichloromethane (2×30 mL), washed with brine (60 mL) and dried over Na2SO4. The solvent was removed and the residue was purified by prep-TLC with petroleum ether/ethyl acetate (1:1) to yield rac-(3aR,5S,6aS)-2-[4-(trifluoromethoxy)phenyl]hexahydro-1H-spiro[cyclopenta[c]pyrrole-5,2′-oxiran]-1-one