Br[C:2]1[CH:7]=[CH:6][C:5]([S:8][CH3:9])=[CH:4][CH:3]=1.[Li]C(C)(C)C.CCCCC.[O:20]1[CH2:24][CH:23]=[CH:22][C:21]1=[O:25].[CH3:26][Si:27](Cl)([CH3:29])[CH3:28].C([O-])(O)=O.[Na+]>CCOCC.C1COCC1.[Cu]I.CCN(CC)CC>[CH3:26][Si:27]([CH3:29])([CH3:28])[O:25][CH:21]1[CH2:22][CH:23]([C:2]2[CH:7]=[CH:6][C:5]([S:8][CH3:9])=[CH:4][CH:3]=2)[CH2:24][O:20]1To a solution of 3.86 g (19 mmol) of 4-bromothioanisole in 90 mL of Et2O cooled at -78° C., is added 22 mL of 1.7M solution of t-BuLi in pentane (38 mmol) dropwise. The reaction mixture is stirred for 15 min at -78° C. and 3.8 g of CuI is added and the reaction mixture is allowed to warm to -40° C. over a period of 30 min. A solution of 1.7 g of 2(5H)-furanone in 10 ml of THF is added. After stirring for 1 h, 2 ml of freshly distilled TMSCl is added dropwise. The reaction mixture is then treated with 2 ml of Et3N and 50 ml of sat. NaHCO3, and extracted with 100 ml of ether. The ether layer is dried over Na2SO4 and concentrated to the crude title compound which is used for the next step without further purification.
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