A 100 ml round bottom flask was charged with {1-[4′-(5-tert-butyl-[1,3,4]oxadiazol-2-ylamino)-biphenyl-4-yl]-2-oxa-bicyclo[2.2.2]oct-4-yl}-acetic acid methyl ester (0.27 g, 0.454 mmol), and lithium hydroxide monohydrate (0.229 g, 5.45 mmol) in tetrahydrofuran (20 ml), ethanol (10 ml) and water (8 ml) at room temperature. The mixture was heated at 50° C. for 2 hours. Most of the organic solvent was evaporated under vacuum and the mixture was acidified to PH=4 at 0° C. The solvents were then removed by lipherlizer. The mixture was added ethanol (40 ml) and heated to 70° C., and then was cooled to room temperature. The mixture was filtered and the solid was washed with ethanol (3 ml) and water (10 ml) to afford {1-[4′-(5-tert-butyl-[1,3,4]oxadiazol-2-ylamino)-biphenyl-4-yl]-2-oxa-bicyclo[2.2.2]oct-4-yl}-acetic acid (150 mg, 71%) as white solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 1.64-1.89 (m, 6H) 2.00-2.13 (m, 4H) 3.85 (s, 2H) 7.42 (d, J=8.40 Hz, 2H) 7.55 (d, J=8.50 Hz, 2H) 7.62 (s, 4H) 10.46 (br. s, 1H). LC/MS, [MS+] 461.23, RT: 2.66 (Condition M).
