To a solution of the intermediate from step D (125 mg, 0.24 mmol) in 5 mL of THF was added MeOH (1 mL) followed by sodium hydroxide (5N, 0.5 mL). After stirring the reaction at room temperature for 18 hours, it was concentrated in vacuo to remove THF/MeOH. The resulting aqueous mixture was acidified with 1N HCl until the pH was slightly acidic (pH=5). The resulting solution was extracted with EtOAc (3×), and the combined organic layers were then washed with brine, dried over anhydrous MgSO4, filtered and concentrated in vacuo. The resulting white solid was used without further purification. LC-MS: 4.03 min; (M+H)=488.3.
