1,2-Bis(diphenylphosphino)ethane → Ethyl cis-1-benzyl-4-(1-tert-butoxycarbonylaminocyclopropyl)pyrrolidine-3-carboxylate

Under a nitrogen gas stream, bis(bicyclo[2.2.1]hepta-2,5-diene)rhodium (I) perchlorate (54.5 mg, 0.14 mmol) and 1,2-bis(diphenylphosphino)ethane (67.4 mg, 0.17 mmol) were dissolved in degassed methanol (25 ml) and stirred at room temperature for 10 minutes. To this catalyst solution was added a solution of ethyl 1-benzyl-4-(1-tert-butoxycarbonylaminocyclopropyl)-3-pyrroline-3-carboxylate (1.090 g, 2.820 mmol) in dry and degassed methanol (15 ml). The thus obtained liquid reaction mixture was then stirred under a hydrogen atmosphere (1 kg/cm2) at room temperature for 2.5 hours. After adding active carbon (1 g), the liquid reaction mixture was allowed to stand at room temperature for 30 minutes and then filtered.through celite (washed with methanol). The filtrate was concentrated under reduced pressure and the residue was subjected to flash silica gel column chromatography (eluent: n-hexane:ethyl acetate=5:1) to obtain 1.071 g (97.8%) of the title compound as colorless crystals.