(R)-quinuclidin-3-ol (214 mg, 1.68 mmol), N,N′-methanediylidenedicyclohexanamine (347 mg, 1.68 mmol) and 1H-benzo[d][1,2,3]triazol-1-ol (227 mg, 1.68 mmol) were added to a solution of (R)-2-(benzyloxycarbonylamino)-2-phenylacetic acid (400 mg, 1.40 mmol) in THF (15 ml). The reaction was stirred at RT for 15 hours, and then the solvent was evaporated. DCM was added, and the insoluble solid was removed by filtration. The organic phase was washed twice with Na2CO3 and brine, dried over Na2SO4 and evaporated. The crude was purified by silica gel flash chromatography (DCM/MeOH=9/1) to obtain (R)—((R)-quinuclidin-3-yl) 2-(benzyloxycarbonylamino)-2-phenylacetate (63 mg; 11.4% yield). ((R)-quinuclidin-3-yl 2-(benzyloxycarbonylamino)-2-phenylacetate is also collected (300 mg; 54.2% yield)).
