GENERAL METHOD: Indole-6-carboxaldehyde (435 mg, 3 mmol) was dissolved in acetonitrile (30 mL), cesium carbonate (829 mg, 6 mmol) was added, and the reaction mixture was heated and refluxed for 2 hours. Subsequently, iodomethane (3.3 mmol) was added to the reaction system and heating and refluxing was continued for 1 hour. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. Water was added to the residue and extracted three times with ethyl acetate. The organic phases were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure. Finally, the resulting residue was purified by fast column chromatography to give the target product 1-methylindole-6-carbaldehyde.
[1] Bioorganic and Medicinal Chemistry, 2014, vol. 22, # 7, p. 2060 - 2079
[2] Journal of Medicinal Chemistry, 2005, vol. 48, # 19, p. 5888 - 5891
[3] Patent: WO2004/52890, 2004, A1. Location in patent: Page 46-47