To a solution of 295 mg of rac-(1R*,2R*,4R*)-2-(2-{[3-(4-methoxy-1H-benzoimidazol-2-yl)-propyl]-methyl-amino}-ethyl)-5-phenyl-bicyclo[2.2.2]oct-5-en-2-ol in 6.6 mL of DCM was added 1.4 mL of NEt3, 81 mg of DMAP and 0.8 mL of 2-methoxy-2-methyl propanoyl chloride (prepared as in JOC, 1976, 41, 19, 3182-3187) at 0° C. The reaction mixture was allowed to warm up to rt and stirred for 5 min at rt before 0.3 mL of anh. THF was added. The reaction mixture was stirred overnight at 50° C., extracted with DCM and washed with sat. NaHCO3. The organic phase was dried over anh. Na2SO4 and concentrated in vacuo. The crude product was purified by CC using DCM/MeOH/DIPEA 95/5/1 to yield 214 mg of rac-2-methoxy-2-methyl-propionic acid (1R*,2R*,4R*)-2-(2-{[3-(4-methoxy-1H-benzoimidazol-2-yl)-propyl]-methyl-amino}-ethyl)-5-phenyl-bicyclo[2.2.2]oct-5-en-2-yl ester as white foam.
