2-(Phenylamino)-2-(thiophen-2-yl)acetic acid hydrochloride (I89) (359 mg, 1.33 mmol), DCC (330 mg, 1.60 mmol) and HOBT (245 mg, 1.60 mmol) are dissolved in THF (15 mL). (R)-quinuclidin-3-ol (339 mg, 2.66 mmol) is added and the reaction mixture is stirred at RT for 16 hours. HOBT (20.4 mg, 0.13 mmol) and DCC (33.0 mg, 0.16 mmol) are added again and the mixture is stirred for additional 8 hours. HOBT (20.4 mg, 0.13 mmol), DCC (33.0 mg, 0.16 mmol), (R)-quinuclidin-3-ol (16.9 mg, 0.13 mmol) are added and the mixture is stirred for additional 16 hours. THF is evaporated and the resulting crude oil is dissolved in EtOAc and washed with water and brine. The organic phase is recovered, dried over Na2SO4, filtered and evaporated. The crude is first purified by flash chromatography (DCM/MeOH=9/1) and then by preparative HPLC. The pure fractions are collected and evaporated. The resulting TFA salt is dissolved in THF and passed through a PL-HCO3 cartridge (Varian, 200 mg, 1.8 mmol/g HCO3−). THF is evaporated, the product is dissolved in dioxane (2 mL) and 4M HCl in dioxane (2 mL) is added. The solvent is evaporated and the residue is dried under vacuum for 24 h to obtain the title compound as a brown solid (33 mg, 7% yield, mixture of disateroisomers).
