[Li]CCCC.Br[C:7]1[CH:11]=[CH:10][O:9][CH:8]=1.CON(C)[C:15](=[O:25])[CH2:16][NH:17][C:18](=[O:24])[O:19][C:20]([CH3:23])([CH3:22])[CH3:21].C([O-])(O)=O.[Na+]>CCOCC.C1COCC1>[O:9]1[CH:10]=[CH:11][C:7]([C:15](=[O:25])[CH2:16][NH:17][C:18](=[O:24])[O:19][C:20]([CH3:21])([CH3:22])[CH3:23])=[CH:8]1
To a solution of n-BuLi (2.5 M in hexane, 7.68 mL) in anhydrous ether (10 mL) was added dropwise (over a 20-min period) a solution of 3-bromofuran (2.35 g, 16 mmol) in anhydrous THF (15 mL) under nitrogen atmosphere at −78° C. After stirring at −78° C. for 20 min, a solution of the Weinreb amide 45 (1.75 g, 8 mmol) in THF (15 mL) was added slowly to the mixture. The reaction mixture was allowed to warm to room temperature and stirred for 18 h. The mixture was poured into a saturated NaHCO3 solution and extracted with EtOAc. The organic phase was dried over anhydrous MgSO4, filtered and evaporated under vacuum. The residue was further purified by silica column chromatography to provide the titled compound (671 mg, 37%). MNa+248.
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