Indole → 1-Methylindole

Participants

Reaction Conditions

Reaction Steps

Indole (10 g, 85.4 mmole), potassium carbonate (5 g), N,N-dimethylformamide (70 mL) and dimethyl carbonate (11 mL, 0.13 mol) were mixed together and refluxed (˜130° C.) for 2 h. At this point TLC analysis of the reaction showed two compounds, the N-methylated indole along with a significant amount of starting material. The reaction mixture was cooled down to ˜50° C. and a second portion of dimethyl carbonate (5.5 mL, 0.065 mol) was added. The mixture was heated at reflux for another 7 h until TLC analysis indicated total consumption of starting indole. The reaction mixture was cooled down to room temperature and it was slowly diluted with water (150 mL). The resulting mixture was extracted with tert-butyl methyl ether (150 mL) and the separated organic layer was washed with water (2×100 mL). The solvent was evaporated in vacuao to furnish 10.8 g of 1-methylindole as light yellow oil (96.5% yield).

Provenance & Evidence