N-Alkylation of heterocyclic compounds bearing an acidic hydrogen atom attached to nitrogen with alkyl halides is accomplished in ionic liquids ([bmim]BF4 = 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]PF6 = 1-butyl-3-methylimida-zolium hexafluorophosphate, [buPy]BF4 = butylpyridinium tetrafluoroborate) in the presence of potassium hydroxide as a base. In this manner, phthalimide, indole, benzimidazole, succinimide can be successfully alkylated. The procedure is convenient, efficient, and generally affords the N-alkylated product exclusively.
- ionic liquids
Le, Z-G., Chen, Z-C., Hu, Y., & Zheng, Q. (2004). Organic reactions in ionic liquids: N-alkylation of phthalimide and several nitrogen heterocycles. Synthesis, 2004(2), 208-212. https://doi.org/10.1055/s-2003-44383