[Cl:1][C:2]1[C:7]([CH:8]=O)=[CH:6][N:5]=[C:4]2[N:10]([Si](C(C)C)(C(C)C)C(C)C)[CH:11]=[CH:12][C:3]=12.C([O-])([O-])=[O:24].[K+].[K+].[O:29]1[CH2:34][CH2:33]O[CH2:31][CH2:30]1>CCOC(C)=O>[Cl:1][C:2]1[C:7](/[CH:8]=[CH:31]/[C:30]([O:29][CH2:34][CH3:33])=[O:24])=[CH:6][N:5]=[C:4]2[NH:10][CH:11]=[CH:12][C:3]=12To a solution of compound 4.0 4-chloro-1-(triisopropylsilyl)-1H-pyrrolo[2,3-b]pyridine-5-carbaldehyde (1.7 g, 5 mmol, 1 equiv.) in dioxane (20 mL) at room temperature was added triethyl phosphonoacetate (3 mL, 15 mmol, 3 equiv.) and K2CO3 (3.45 g, 25 mmol, 5 equiv.). The resulting mixture was heated overnight at 80° C. under argon. Upon cooling to room temperature, the mixture was diluted with EtOAc (50 mL) and washed with water (50 mL) and brine (50 mL). The organic phase was dried over Na2SO4, after removal of solvent under vacuum. The resulting residue was purified with flash chromatography (Hexanes: EtOAc=6:1) to afford the desired product 4.1 (E)-ethyl 3-(4-chloro-1H-pyrrolo[2,3-b]pyridin-5-yl)acrylate (0.63g; 50%). LC-MS:(M+H) 251.29
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