6-bromo-2-methyl-1H-indole

Conditions: temp:-40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 6-bromo-2-methyl-1H-indole (2.0 g, 9.52 mmol) in dry tetrahydrofuran (100 mL) was added sodium hydride (381 mg, 9.53 mmol) with ice-cooling. After stirring for about 30 min, a solution of n-BuLi (15 mL, 2.5 M solution in hexane) was added dropwise with stirring at −78° C. under nitrogen. It was warmed slowly to −40° C. during 45 min and stirred at this temperature for another 30 min. The mixture was cooled again below −78° C. followed by dropwise addition of 4,4,5,5-tetramethyl-2-(propan-2-yloxy)-1,3,2-dioxaborolane (3.54 g, 19.03 mmol). After warming to room temperature, the mixture was quenched with NH4Cl (aq) and extracted with ethyl acetate (3×80 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the residue, which was purified by silica gel column chromatography (2% ethyl acetate in petroleum ether) to afford 2-methyl-6-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indole (1.2 g, 49%). cooling with stirring at −78° C. under nitrogen stirred at this temperature for another 30 min The mixture was cooled again below −78° C. After warming to room temperature the mixture was quenched with NH4Cl (aq) extracted with ethyl acetate (3×80 mL) The combined organic layers were dried over anhydrous sodium sulfate filtered concentrated under reduced pressure to give the residue, which was purified by silica gel column chromatography (2% ethyl acetate in petroleum ether)