[CH3:1][O:2][C:3](=[O:14])[CH2:4][C:5]1[CH:10]=[CH:9][C:8]([Cl:11])=[C:7]([O:12][CH3:13])[CH:6]=1.[Li][CH2:16]CCC.C(NC(C)C)(C)C.CI>C1COCC1>[Cl:11][C:8]1[CH:9]=[CH:10][C:5]([CH:4]([CH3:16])[C:3]([O:2][CH3:1])=[O:14])=[CH:6][C:7]=1[O:12][CH3:13]The product of step (i) (0.5 g) was added to a solution of nBuLi (1.75 ml, 1.6 M in THF) and diisopropylamine (0.4 ml) in THF (10 ml) at −78° C. and stirred for 1 h, then methyl iodide (0.18 ml) was added, stirred for 1 h at −78° C. then at room temperature for 1 h and quenched with water. The product was extracted with ether, dried (MgSO4) and evaporated under reduced pressure. The residue was purified by flash column chromatography (eluent 1:1 isohexane/ether) to give the subtitle compound (0.21 g).
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