[CH3:1][O:2][C:3](=[CH2:8])[C:4]([O:6][CH3:7])=[O:5].CO[CH2:11][N:12]([CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)[CH2:13][Si](C)(C)C.FC(F)(F)C(O)=O>ClCCl>[CH3:7][O:6][C:4]([C:3]1([O:2][CH3:1])[CH2:8][CH2:11][N:12]([CH2:18][C:19]2[CH:20]=[CH:21][CH:22]=[CH:23][CH:24]=2)[CH2:13]1)=[O:5]To a stirred solution of methyl 2-methoxyacrylate (20.8 g, 179 mmols) and N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine (55 ml, 215 mmols) in dichloromethane (160 ml) was added at 0 C a solution of trifluoroacetic acid (2 ml) in dichloromethane (10 ml). The resulting solution was warmed to room temperature and stirred overnight. After concentration, the crude product was purified by column chromatography on silica gel eluting with a solution of ethyl acetate/hexanes/Et3N (1000:3000:4 to 1000:1000:3) to give the title compound (17.7 mg, 40%).
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