[NH:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]1=[O:7].[Li+].[CH3:9]C([N-]C(C)C)C.[C:16](=[O:18])=[O:17].Cl.[CH2:20]1[CH2:24]O[CH2:22][CH2:21]1>>[CH2:22]([N:1]1[CH:6]=[CH:5][C:4]([CH2:9][C:16]([OH:18])=[O:17])=[CH:3][C:2]1=[O:7])[CH2:21][CH2:20][CH3:24]A solution of pyridinone ix (1.7 g, 10.3 mmol) in 20 mL anhydrous THF is added dropwise to a solution of LDA (2 M, 5.7 mL, 6.05 mmol) in 40 mL anhydrous THF at −78° C. The solution is allowed to stir for 45 minutes followed by the addition of solid CO2 (10 g). After 0.5 h the mixture is poured onto H2O and acidified with 1 N HCl. The solution is concentrated under reduced pressure and extracted with ethyl acetate and CH2Cl2. The combined organics are dried over MgSO4, filtered and concentrated to give a solid which is purified by flash chromatography (9/1:CH2Cl2/MeOH) to provide x as a white solid (1.4 g, 66%). (MS: M+H: 210.0).
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