[CH:1]1[C:10]2[CH2:9][CH2:8][CH2:7][CH2:6][C:5]=2[CH:4]=[CH:3][C:2]=1[S:11]([NH:14][C:15]1[CH:19]=[CH:18][S:17][C:16]=1[C:20]([O:22]C)=[O:21])(=[O:13])=[O:12].[OH-].[Na+].CO>O1CCCC1>[CH:1]1[C:10]2[CH2:9][CH2:8][CH2:7][CH2:6][C:5]=2[CH:4]=[CH:3][C:2]=1[S:11]([NH:14][C:15]1[CH:19]=[CH:18][S:17][C:16]=1[C:20]([OH:22])=[O:21])(=[O:12])=[O:13]To a solution of 78 (71 mg, 0.20 mmol) in tetrahydrofuran (1 mL) were added aqueous sodium hydroxide (2 mL; 2N) and methanol (2 mL). The reaction mixture was heated at 50° C. for 27 hours, allowed to cool to room temperature, and then extracted with aqueous sodium hydroxide (20 mL; 2N). The aqueous layer was washed with diethyl ether (30 mL×2), acidified with aqueous hydrochloric acid (20 mL; 6N), and extracted with dichloromethane (40 mL). The organic layer was separated, dried over magnesium sulfate, and filtered. The filtrate was concentrated under reduced pressure to yield the title compound as a white solid (51 mg).
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