Br[C:2]1[CH:3]=[C:4]2[CH:10]=[CH:9][N:8]([Si:11]([CH:18]([CH3:20])[CH3:19])([CH:15]([CH3:17])[CH3:16])[CH:12]([CH3:14])[CH3:13])[C:5]2=[N:6][CH:7]=1.[Li]C(C)(C)C.CCCCC.[CH:31](N1CCCCC1)=[O:32].[NH4+].[Cl-]>C1COCC1.CCCCCC.CCOCC>[CH:12]([Si:11]([CH:18]([CH3:20])[CH3:19])([CH:15]([CH3:17])[CH3:16])[N:8]1[C:5]2=[N:6][CH:7]=[C:2]([CH:31]=[O:32])[CH:3]=[C:4]2[CH:10]=[CH:9]1)([CH3:14])[CH3:13]Bromide x254 (1.1 g, 3.11 mmol) is dissolved in freshly distilled absolute THF (40 ml). A 1.7 M solution of t-BuLi in pentane (1.92 ml, 1.05 eq) is added dropwise at −100° C. under vigorous stirring in a flow of argon. The reaction mixture is stirred for 45 min and meanwhile allowed to heat up slowly to −78° C. After this, a solution of N-formylpiperidine (0.42 g, 1.2 eq, 3.73 mmol) in freshly distilled absolute THF (5 ml) is added dropwise for 5 min. The mixture is allowed to heat up to 0° C. under stirring in the cooling bath, and then poured into a mixture of saturated aqueous NH4Cl (20 ml) and 1:1 hexane/ether mixture (100 ml). The organic phase is separated, dried with anhydrous sodium sulfate, and evaporated. The residue is purified by chromatography on silicagel, CCl4/MeCN) to afford 0.7 g of 1-(triisopropylsilyl)-1H-pyrrolo[2,3-b]pyridine-5-carbaldehyde x255.
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