[CH3:1][C:2]1([CH3:19])[CH:11]=[C:10]([C:12]2[S:13][C:14]([CH3:17])=[CH:15][CH:16]=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:28]=[O:29])C>C1COCC1.CCCCC.C(OCC)(=O)C>[CH3:1][C:2]1([CH3:19])[CH:11]=[C:10]([C:12]2[S:13][C:14]([CH3:17])=[CH:15][CH:16]=2)[C:9]2[C:4](=[CH:5][CH:6]=[C:7]([CH:28]=[O:29])[CH:8]=2)[O:3]1To a cold (-78° C.) solution of 2,2-dimethyl-4(5-methyl-thien-2-yl)-6-bromo-chrom-3-ene (Compound R, 1.2 g, 3.6 mmol) in THF (10 mL), was added t-BuLi in pentane (1.7M solution, 2.3 mL). After 30 minutes, DMF (465 mg, 5 mmol) was added and the mixture was allowed to warm to ambient temperature and stirred for 3 hours. The mixture 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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