C([Li])CCC.C(P([CH2:12][S:13]([O:16][CH2:17][CH3:18])(=[O:15])=[O:14])(CC)=O)C.[CH3:19][C:20]1[S:24][C:23]([CH:25]=O)=[CH:22][CH:21]=1>C1COCC1>[CH3:25][C:23]1[S:24][C:20]([CH:19]=[CH:12][S:13]([O:16][CH2:17][CH3:18])(=[O:14])=[O:15])=[CH:21][CH:22]=1n-Butyl lithium (1.6 mL of a 2.5 M solution in hexanes, 4.0 mmol) was added dropwise to a solution of ethyl diethylphosphorylmethanesulfonate (1.0 g, 3.8 mmol), prepared as described in Tetrahedron, 1987, 43(21), 5125, at −78° C. in THF (15 mL). The mixture was stirred for 20 min. then 5-methyl-2-thiophenecarboxaldehyde (460 mg, 4.2 mmol) was slowly added. The mixture was stirred at −78° C. for 1 h. then allowed to warm to room temperature overnight. The bulk of the solvents were evaporated and the residue was treated with water (2 mL) and extracted with CH2CL2. The organic layer was washed with brine, dried over MgSO4, filtered and concentrated. The crude product was purified by column chromatography eluting with CH2CL2 to give the title compound.
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