Triisopropylsilyl chloride → 7-iodo-5-triisopropylsilanyl-2-(3,4,5-trimethoxy-phenyl)-5H-pyrrolo[2,3-b]pyrazine

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A solution of 7-iodo-2-(3,4,5-trimethoxy-phenyl)-5H-pyrrolo[2,3-b]pyrazine (6.7 g, 16.29 mmol) in anhydrous tetrahydrofuran (150 ml) was cooled to 0° C. and treated with potassium bis(trimethylsilyl)amide (0.5M in toluene, 35.85 ml, 17.9 mmol) dropwise. After complete addition, the reaction mixture was stirred at room temperature for 1 hour, treated dropwise with chloro-triisopropyl-silane (3.9 ml, 18.4 mmol), and allowed to stir at room temperature for 16 hours. Chloro-triisopropyl-silane (1.0 ml, 4.7 mmol) was added, and the reaction mixture was stirred at room temperature for 16 hours, and then at 60° C. for 16 hours. The reaction mixture was partitioned between EtOAc/saturated aqueous NH4Cl. The organic layers were collected, dried over MgSO4, filtered, and concentrated giving a dark solid. The residue was purified by silica gel chromatography using 3-100% EtOAc in hexanes as eluant to provide 7.4 g (80%) of 7-iodo-5-triisopropylsilanyl-2-(3,4,5-trimethoxy-phenyl)-5H-pyrrolo[2,3-b]pyrazine as a white solid. MP 156.5-157.2, M+H=568.

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