Modular Synthesis of gamma-Valerolactone-Based Ionic Liquids and Their Application as Alternative Media for Copper-Catalyzed Ullmann-type Coupling Reactions

摘要

A convenient procedure was developed for the manufacturing of partially bio-ionic liquids (ILs) from renewable gamma-valerolactone (GVL) and cheap and readily available tetraalkylphosphonium bromides with excellent (99%) yields. The novel ionic liquids were characterized by their temperature dependent vapor pressure, density, viscosity, and conductivity. We have proven that these ILs can be a useful medium for copper-catalyzed Ullmann-type coupling reactions without the use of any ligand or additive, representing an environmentally benign tool for the synthesis of various amines. Twenty cross-coupling products were isolated with good to excellent yields (50-87%).