To a stirred mixture of 1-(4-nitrophenyl)tricyclo[3.3.1.03,7]nonan-3-amine (2.0 g, 8.0 mmol) obtained in step III, K2CO3 (3.5 g, 24 mmol) in THF (80 mL), cooled to ice-bath temperature was added benzylchloroformate (50% w/v in Toluene, 2.2 mL, 12 mmol). After stirring the reaction mixture at r.t for 2 h, it was diluted with water and extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4, and the solvent was removed under reduced pressure to obtain benzyl[2-(4-nitrophenyl)hexahydro-2,5-methanopentalen-3a(1H)-yl]carbamate as an off-white solid (2.1 g) in 70% yield. M.R: 104.1-105.9° C.; m/z (M+1) 393; IR cm−1 3440, 2952, 1714, 1518, 1349, 1216, 757; 1H NMR (CDCl3) 300 MHz δ 8.12 (d, J=8.8 Hz, 2H), 7.50-7.27 (m, 7H), 5.20-5.0 (s (br), 2H), 2.65-2.55 (m, 1H), 2.50-1.55 (m, 11H). 13C NMR (CDCl3) 75 MHz δ 155.1, 154.2, 146.1, 136.4, 131.1, 128.5 (2C), 128.1 (2C), 126.6 (2C), 123.4 (2C), 66.3, 64.4, 49.248.0, 47.5, 43.8, 42.1, 40.8, 37.0.
