Magnetically Recyclable Heterogeneous Cobalt Ferrite Catalyst for the Direct N‐Alkylation of (Hetero)aryl Amines with Alcohols

Abstract

AbstractHerein we report the use of spinel cobalt ferrite nanoparticles as an efficient and selective catalyst for the mono N‐alkylation of aryl and hetero aryl amines with various aromatic and aliphatic alcohols. Based on our experiments, the optimum condition for good to excellent yield were observed with alcohol (1.0 mmol), aniline (1.2 mmol), KOH (0.5 equiv), and CoFe2O4 nanocatalyst (10 mol%) in toluene at 130 °C in 24 hours. Further control experiment studies revealed that the reaction does not proceed in the absence of the catalyst or a strong base. This magnetically recyclable nanocatalyst does not require any ligands and is easily synthesized at low temperature. The reutilization of the recovered catalyst in a fresh reaction gave good to excellent yield. The experiment results strongly suggest a borrowing hydrogen pathway for N‐alkylation under our standard conditions. The utility of these nanocatalysts was also demonstrated for the dehydrogenative synthesis of heterocycles like indole and quinolines.