2-Bromopropane → methyl 6-bromo-1-isopropyl-1H-indole-4-carboxylate

Participants

Reaction Steps

To a cooled (0° C.) solution of methyl 6-bromo-1H-indole-4-carboxylate (1.0 g, 3.94 mmol) solid in N,N-dimethylformamide (25 mL) was added sodium hydride (0.173 g, 4.33 mmol). The reaction was stirred for 15 min, at which time 2-bromopropane (0.554 mL, 5.90 mmol) was added. The reaction was then allowed to warm to RT and was maintained overnight. LCMS showed about 25% starting material remaining. The reaction was heated at 45° C. for 4 h, but no further conversion was noted. The reaction vessel was put back into an ice bath and stirred for 15 min. Then excess NaH (60%) was added, stirred for 10 min, and then 2-bromopropane (excess) was added. The ice bath was removed and the reaction stirred for 1 h. Approximately half of the reaction volume was removed in vacuo and poured into saturated NH4Cl (200 mL). This was extracted with ether (2 x) and the combined organics were washed with brine, dried (MgSO4), and concentrated. Purification by column chromatography (80 g Isco silica column; Gradient B: 5-25%, A: hexane, B: ethyl acetate) gave methyl 6-bromo-1-(1-methylethyl)-1H-indole-4-carboxylate (0.53 g, 1.718 mmol, 43.7% yield).

Provenance & Evidence