To a solution of tert-butyl [(1S)-3-oxo-1-phenylpropyl]carbamate from Step B (0.820 g, 3.29 mmol) and methyl 1-aminocyclopentanecarboxylate hydrochloride (0.591 g, 3.29 mmol) in chloroform (33 mL) was added Hunig's base (0.574 mL, 3.29 mmol). After stirring at ambient temperature for 20 min, NaHB(OAc)3 (1.74 g, 8.22 mmol) was added as a solid. Upon completion of the reaction, saturated aqueous NaHCO3 (3 mL) was added and the mixture was allowed to stir for at least 2 h. Water (5 mL) and additional saturated NaHCO3 (3 mL) was then added to form two layers. The aqueous layer was extracted once with chloroform (50 mL). The combined organic layers were dried over sodium sulfate, filtered and concentrated in vacuo to give an oil. This oil was purified by silica gel chromatography, eluting with a gradient of MeOH:DCM 1:99 to 6:94, to give the title compound. MS: m/z=377 (M+1).
