[CH3:1][C:2]1[CH:3]=[C:4]([CH2:11][CH:12]=[CH:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])[CH:5]=[C:6]2[C:10]=1[NH:9][N:8]=[CH:7]2.C1(C(N)C2CCCCC2)CCCCC1.[CH3:33][Si:34]([CH3:41])([CH3:40])[CH2:35][CH2:36][O:37][CH2:38]Cl>O1CCCC1>[CH3:1][C:2]1[C:10]2[C:6](=[CH:7][N:8]([CH2:38][O:37][CH2:36][CH2:35][Si:34]([CH3:41])([CH3:40])[CH3:33])[N:9]=2)[CH:5]=[C:4]([CH2:11][CH:12]=[CH:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])[CH:3]=1To the clear solution of ethyl 4-(7-methyl-1H-indazol-5-yl)but-2-enoate (760 mg, 3.11 mmol, 1.0 equiv.) in tetrahydrofuran (10 mL) was added dicyclohexylmethyl amine (2.6 mL, 6.2 mL, 2.0 equiv) followed by 2-(trimethylsilyl)ethoxymethyl chloride (0.66 mL, 3.73 mmol, 1.2 equiv). The reaction mixture was stirred at room temperature for 2 h. The mixture was partitioned between 0.5 N sodium hydroxide and ethyl acetate. The organic layer was separated and washed with brine, dried over sodium sulfate and concentrated in vacuo. The residual colorless oil was purified by flash column chromatography (20% ethyl acetate in hexanes) to afford the desired product as a colorless oil (1.08 g, 93%). MS (ESI) [M+H]+=375.
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