[S:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6]([OH:8])=[O:7].[Li+].[CH3:10][CH:11]([N-]C(C)C)[CH3:12].[Br:17]C(Br)(C)C.[Cl-].[NH4+].[Cl-].[Na+].Cl>C1COCC1>[Br:17][CH2:10][CH2:11][CH2:12][C:5]1[S:1][C:2]([C:6]([OH:8])=[O:7])=[CH:3][CH:4]=1To a solution consisting of thienoic acid (10 g, 78 mmol) in THF (150 mL) at −78° C. was added an LDA solution (85 mL, 170 mmol, 2 M in heptanes/THF/ethylbenzene, Sigma-Aldrich) dropwise over 20 minutes, and the reaction mixture was stirred 40 minutes. To the reaction mixture was then added dibromopropane (23.8 g, 117 mmol) in one portion, and the reaction mixture was allowed to warm to room temperature and was stirred for 3 days. To the reaction mixture was added 50 mL each of a saturated aqueous solution of ammonium chloride, a saturated aqueous solution of sodium chloride, and 6 N HCl. The organic material was extracted with ethyl acetate and the organic layer was dried over sodium sulfate, filtered, and concentrated to afford the title compound as a yellow oil (24.0 g). The product was used without further purification; TLC Rf 0.5 (solvent system: 30:70:1 v/v ethyl acetate-hexanes-acetic acid).
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