[CH3:1][O:2][C:3]1[C:12]2[C:7](=[CH:8][CH:9]=[CH:10][CH:11]=2)[C:6]([O:13][CH3:14])=[CH:5][C:4]=1[O:15][CH3:16].[Li]CCCC.CN([CH:25]=[O:26])C>C1COCC1>[CH3:14][O:13][C:6]1[C:7]2[C:12](=[CH:11][CH:10]=[CH:9][CH:8]=2)[C:3]([O:2][CH3:1])=[C:4]([O:15][CH3:16])[C:5]=1[CH:25]=[O:26]According to the procedure by Syper et al.,38 100 (1.07 g, 4.90 mmol) was dissolved in THF (20.0 mL) at 0° C. under Argon, and then nBuLi (1.6 M in hexanes, 4.0 mL, 10.0 mmol) was added at 0° C. The reaction was stirred at 0° C. for 5 hours before DMF (0.850 mL, 11.0 mmol) was added at 0° C. The reaction was stirred for another 30 minutes at room temperature before quenching with water. The reaction was diluted with ethyl ether and washed with saturated brine. The organic layer was dried over MgSO4, filtered, and condensed. Crude product was used as a 5:1 mixture of product:starting material, affording 54 (1.07 g, 4.35 mmol, 89%) as a yellow oil. Following purification via column chromatography (CH2Cl2 to 1:9 EtOAc:CH2Cl2) pure aldehyde 54 was obtained as a yellow solid.
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