N-Alkylation of Pyrrole, Indole, and Several Other Nitrogen Heterocycles Using Potassium Hydroxide as a Base in the Presence of Polyethylene Glycols or Their Dialkyl Ethers

Article abstract of DOI:10.1246/bcsj.56.280

The alkylation of pyrrole and indole in aqueous potassium hydroxide-organic two-phase systems in the presence of polyethylene glycols (PEG) or their dialkyl ethers (PEG-ether) as phase transfer catalysts (PTC) gave substantial quantities of the C-alkylated and C,N-polyalkylated products as well as the N-alkylated products.This fact is similar to that obtained in the presence of quaternary ammonium salts as PTC.In powdered potassium hydroxide-organic two-phase system, the yields of the N-alkylated products were generally high.Especially, when PEG-ether were employed as solvents, the N-alkylated products were obtained in excellent yields under mild conditions.Imidazole, benzimidazole, carbazole, 2-methylindole, and benzotriazole were similarly N-alkylated in high yields by this method.