Lithium borohydride → 5-bromo-7-ethyl-1H-indole

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of 5-bromo-7-ethyl-1H-indole-2,3-dione (36.0 g, 144 mmol) in tetrahydrofuran (120 mL) at room temperature was dropped a 2.0 M solution of lithium borohydride in tetrahydrofuran. The reaction mixture was stirred at 90° C. (oil bath) for 5 hours. After cooling down to room temperature, it was quenched with 5% hydrochloric acid solution until the excess lithium borohydride was destroyed. To the mixture was added saturated sodium bicarbonate solution (300 mL) and extracted with ethyl acetate. Extracts were dried over magnesium sulfate and concentrated under reduced pressure to give the crude product of 5-bromo-7-ethyl-1H-indole, which went to next reaction without further purification.

Herkunft & Nachweise