Indole → 3-Benzoylindole

Participants

Reaction Conditions

Reaction Steps

Magnesium (2.08 g), toluene (40 ml), triethylamine (10.4 g) were put into a 3″ diameter flask, and the internal temperature was raised to 30 to 45° C. A solution of 1-iodebutane (18.9 g) in toluene was added under stirring at an internal temperature of 30 to 45°C. After stirring for two hours at the same temperature, the temperature was lowered to 0 to 5° C., thereby preparing a solution of iode n-butylmagnesium in toluene. To this prepared Grignard reagent, indole (10.0 g) dissolved beforehand in toluene (25 ml) was added at an internal temperature of 0 to 10° C., and a reaction was carried out for about one hour at the same temperature to synthesize iodeindole-1-ylmagnesium. Then, benzoyl chloride (12.0 g) and toluene (60 ml) were put into another 3″ diameter flask, and the internal temperature was lowered to below −15° C. The slurry of the iodeindole-1-ylmagnesium prepared previously was added to the solution of this acid chloride while keeping the internal temperature at −15 to −10° C., and the mixture was stirred for more one hour at the same temperature. The internal temperature was then raised further to 20 to 25° C., and the mixture was stirred for one hour. After this reaction, the mixture was added to an aqueous ammonium chloride solution (16 g, 60 ml) prepared beforehand in another 3″ diameter flask at 10° C. or less to carry out quenching. Acetone (220 ml) was added thereto, the internal temperature was raised to 50 to 65° C., and dissolution was carried out, followed by separation. The organic layer of the upper layer was then collected and cleaned with an aqueous 5% sodium hydrogencarbonate solution at the same temperature. The solvent was evaporated so as to be concentrated. Methanol (20 ml) was added thereto and refluxed. After cooled to an internal temperature of 2 to 10° C., a precipitated crystal was filtered. The filtered crystal was cleaned with cooled methanol (5 ml) and dried to obtain a crystal of 3-benzoylindole (13.7 g) (72.2% yield).

Provenance & Evidence