Synthesis
Sodium hydride (0.35 g, 8.75 mmol) was slowly added to a stirring solution of methyl 1H-indole-6-carboxylate (0.76 g, 4.34 mmol) in N,N-dimethylformamide (DMF, 10 mL) at room temperature. The resulting suspension was stirred continuously at room temperature for 30 min, followed by dropwise addition of iodomethane (0.54 mL, 8.67 mmol). The reaction mixture was continued to be stirred at room temperature for 20 hours. Upon completion of the reaction, water (20 mL) and ethyl acetate (20 mL) were added to quench the reaction. The aqueous phase was extracted with ethyl acetate (3 x 30 mL), and all organic phases were combined and dried over a phase separation column. Subsequently, the solvent was evaporated under reduced pressure to afford methyl 1-methyl-6-indolecarboxylate as an off-white solid (0.85 g, 100% yield). The product (MH+ = 190) was confirmed by LC-MS (acidic conditions). The purity of the obtained product met the requirements for subsequent use without further purification.
References
[1] Patent: WO2009/71577, 2009, A1. Location in patent: Page/Page column 43
[2] Patent: WO2010/84185, 2010, A1. Location in patent: Page/Page column 23
[3] Journal of the American Chemical Society, 2005, vol. 127, # 22, p. 8050 - 8057
[4] Chemical and Pharmaceutical Bulletin, 1999, vol. 47, # 11, p. 1538 - 1548
[5] Heterocycles, 2006, vol. 67, # 2, p. 643 - 653
