Indole → 1-Benzylindole

Participants

Reaction Steps

A mixture of indole (1) (0.03 mole, 3.51 g), potassium hydroxide (0.03 mole, 1.97 g)) powdered in a mortar and 18-crown-6 ether (0.001 mole, 250 mg) in benzene (20 cm3) is heated under reflux with vigorous stirring for two hours. A solution of benzyl chloride (26) (0.04 mole, 5.06 g) in benzene (10 cm3) is added to the above mixture and reflux is maintained for an additional four hours. The reaction is monitored by TLC. The reaction mixture is filtered on Celite. Evaporation of the solvent gives an orange liquid which is purified by dry column chromatography eluted using a mixture of dichloromethane in 50% petroleum ether. Evaporation of the solvent gives a colourless thick liquid which is solidified in the presence of diethyl ether to give a white solid of 1-benzylindole (3b) (1.2 g, 0.007 mole, 25%), m.p. 48-51° C., shown to be pure by 1H nmr.

Provenance & Evidence