A waste-minimized protocol for copper-catalyzed Ullmann-type reaction in a biomass derived furfuryl alcohol/water azeotrope†
We report the use of biomass-derived furfuryl alcohol as an effective bidentate ligand able to promote the Ullmann-type copper-catalyzed coupling of aryl halides with heteroaromatic or aliphatic amines. Furfuryl alcohol (FA) can be mixed with water to form the corresponding azeotrope (20 wt% of FA) and therefore can be easily recovered and reused. This protocol is efficiently applied to substrates with various electronic nature and affords the expected products (27 examples) in generally good to excellent yields. It has also been demonstrated that the protocol is both chemically and environmentally effective as the azeotropic mixture can be easily and almost quantitatively recovered at the end of the process.