To a solution of (4S)-1-[(3S,4R)-4-(4-chlorophenyl)pyrrolidine-3-yl]carbonyl-4-[(4,4-dimethylcyclohexyl)(2,2-dimethylpropanoyl)amino]-N,N-dimethyl-L-prolineamide (100 mg, 0.18 mmol) prepared in Example E1-1 in DCE (5 ml) was added 1-ethoxycyclopropoxytrimethylsilane (47 mg, 0.27 mmol) and sodium-cyanoborohydride (23 mg, 0.36 mmol), added a catalytic amount of acetic acid, and the solution was stirred at 80° C. for 2 h. After the reaction finished, the solvent was concentrated in vacuo, and extracted with a saturated NaHCO3 aqueous solution and EtOAc. The organic solution was dried over MgSO4, concentrated in vacuo, and the residue was purified by HPLC. This TFA salt of the compound was treated according to the procedure described in Step G of Example A1 to give the title compound.
