One-Pot Reductive Amination of Aromatic Aldehydes in Et3NHHSO4 using Sodium Borohydride and A Mechanistic Investigation using Computational Method

摘要

The reductive amination of aromatic aldehydes and aromatic amines, performed in the Bronsted acidic ionic liquid [Et3NH][HSO4], using sodium borohydride as a reducing agent is reported. In this protocol, the ionic liquid plays a crucial role in efficiently converting aromatic aldehydes to amines in excellent yields, without the formation of side products. In the presence of [Et3NH][HSO4], the imine was generated in situ from the reaction between the aromatic aldehydes and aromatic amines, and underwent smooth reduction with sodium borohydride. This one-pot synthesis is practically simple and sustainable. The catalyst [Et3NH][HSO4] also has a demonstrably wide applicability, in that it can be used with a variety of aromatic aldehydes and aromatic amines substituted by various electron-withdrawing and electron-donating groups. The role of IL [Et3NH][HSO4] in catalytic reductive amination is validated with the help of density functional theory (DFT)-based computational studies.