Sodium Chloride → 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-(triisopropylsilyl)-1H-pyrrolo[2,3-b]pyridine

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Reaction Steps

3.00 g of 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrrolo[2,3-b]pyridine are suspended in 40 ml of tetrahydrofuran in a flask. 0.73 g of sodium hydride (60% in paraffin oil) are added in portions with ice-cooling. 3.94 ml of chlorotriisopropylsilane is subsequently added dropwise at about 25° C., and the mixture is heated at 40° C. (bath temperature) under nitrogen until the boronic acid ester has reacted completely (HPLC check, about 5 hours). The excess sodium hydride is deactivated using 10 ml of saturated sodium chloride solution. The solvent is removed in vacuo. The residue is diluted with about 50 ml of water and extracted three times with diethyl ether. The combined organic phases are dried over sodium sulfate and purified by means of column chromatography (gradient heptane: EA 5-100% in 15 min.), giving 4.55 g of 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-triisopropylsilanyl-1H-pyrrolo[2,3-b]pyridine as white solid (yield 92%, content 92%); MS-FAB (M+H+)=401.2; Rf (nonpolar method): 3.61 min.

Provenance & Evidence