Dimethylformamide → Indole-7-carboxaldehyde

Participants

Reaction Conditions

Reaction Steps

A solution of 7-bromoindole [Tet. Lett. 30, 2129 (1989)] (12.75 g, 0.065 mole) in dry tetrahydrofuran (230 ml) was cooled in a dry ice-acetone bath and 2.5M n-butyl lithium in hexane (78 ml, 0.195 mole) added dropwise over 1 hour, maintaining the reaction temperature below -60° C. The reaction mixture was stirred for a further 15 minutes at -70° C., then allowed to warm to 5° C. After 30 minutes at 5° C., the reaction was recooled to -70° C. and dimethylformamide (25 ml, 0.325 mole) added dropwise at a rate to maintain the temperature below -65° C. The mixture was allowed to warm to room temperature slowly, then was poured into water and extracted into diethyl ether. The combined dry extracts were washed with brine, dried and evaporated. Recrystallisation from 80°-100° C. petroleum ether with charcoal treatment yielded the product as fawn-coloured crystals.

Provenance & Evidence