To a cold (0° C.) solution of methyl 6-hydroxynorbornane-2-carboxylate, 72e, (3.2 g, 18.8 mmol) in THF (150 mL) was added ethyl 2-(tert-butoxycarbonylamino)-2-oxo-acetate (4.9 g, 22.6 mmol) and triphenylphosphine (5.9 g, 22.6 mmol) followed by dropwise addition of diisopropyl azodicarboxylate (4.5 g, 22.6 mmol). The reaction was then heated to 85° C. and maintained at that temperature for 2 days. The solvent was evaporated under reduced pressure and the crude product was purified by silica gel chromatography (0-100% EtOAc/hexanes gradient) to provide 6 g of methyl 6-(N-(tert-butoxycarbonyl)-2-ethoxy-2-oxoacetamido)bicyclo[2.2.1]heptane-2-carboxylate: LCMS 392.34 (M+Na+); 1H NMR (300 MHz, CDCl3) δ 4.26 (q, J=7.2 Hz, 2H), 4.08 (dt, J=14.3, 7.2 Hz, 1H), 3.62 (d, J=2.1 Hz, 3H), 2.72 (s, 1H), 2.42-2.26 (m, 2H), 2.08-1.80 (m, 2H), 1.80-1.51 (m, 3H), 1.45 (s, 9H), 1.38-1.25 (m, 3H).
