To a stirred mixture of the compound obtained from step II (0.4 g, 1.35 mmol) and K2CO3 (0.56 g, 4.05 mmol) in DMSO (6 mL) at ice bath temperature under N2 atmosphere was added (S)-1-(2-chloro-acetyl)pyrrolidine-2-carbonitrile (0.23 g, 1.35 mmol). The reaction mixture was gradually warmed to room temperature and stirred for 3 h. Upon completion of the reaction (checked by TLC), the reaction mixture was diluted with EtOAc and washed with water and brine, dried over Na2SO4, and the solvent was evaporated under reduced pressure. The crude product was purified by column chromatography to obtain (2S)-1-{N-[2-[4-(2-oxoimidazolidin-1-yl)phenyl]hexahydro-2,5-methanopentalen-3a(1H)-yl]glycyl}pyrrolidine-2-carbonitrile as an off-white solid (0.21 g) in 36% yield. m/z (M+1) 434; 1H NMR (CDCl3) 300 MHz δ 7.45 (d, J=8.8 Hz, 2H), 7.23 (d, J=8.8 Hz, 2H), 4.86-4.76 (m, 1H), 4.67 (s (br), 1H), 3.93 (t, J=7.4 Hz, 2H), 3.75-3.40 (m, 4H), 3.48 (s, 2H), 3.46-2.38 (m, 1H), 2.36-2.23 (m, 2H), 2.23-1.70 (m, 12H), 1.65-1.57 (m, 1H).
