[CH3:1][C:2]1([CH3:20])[CH:11]=[C:10]([C:12]2[CH:17]=[CH:16][C:15]([CH3:18])=[CH:14][CH:13]=2)[C:9]2[C:4](=[CH:5][CH:6]=[C:7](Br)[CH:8]=2)[O:3]1.[Li]C(C)(C)C.CN([CH:29]=[O:30])C>C1COCC1.CCCCC.C(OCC)(=O)C>[CH3:1][C:2]1([CH3:20])[CH:11]=[C:10]([C:12]2[CH:17]=[CH:16][C:15]([CH3:18])=[CH:14][CH:13]=2)[C:9]2[C:4](=[CH:5][CH:6]=[C:7]([CH:29]=[O:30])[CH:8]=2)[O:3]1To a cold (-78° C.) solution of 2,2-dimethyl-4(tol-4-yl)-6-bromo-chrom-3-ene (Compound P, 480 mg, 1.45 mmol) in THF (10 mL), was added t-BuLi in pentane (1.7M solution, 1.1 mL) and the mixture was stirred for 30 minutes. DMF (200 mg, 2.9 mmol) was added, the mixture was warmed to ambient temperature and stirred for 3 hours. The reaction was diluted with ethyl acetate (150 mL), washed with brine (10 mL), dried and the solvent was removed by evaporation. Purification by chromatography on silica gel column gave the title compound as a colorless oil.
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