Efficient Copper‐Catalyzed Ullmann Reaction of Aryl Bromides with Imidazoles in Water Promoted by a pH‐Responsive Ligand

Abstract

A series of 1,10‐phenanthroline derivatives were used as supporting ligands for copper‐catalyzed Ullmann reaction in neat water. The catalytic system based on 4,7‐dihydroxy‐1,10‐phenanthroline has demonstrated the promising catalytic performances for aryl bromides. The catalytic system was applicable to a wide scope of substrates, high catalytic activity and selectivity were observed for the reactions of electron‐deficient, electron‐rich, and heterocyclic aryl bromides with imidazoles containing different steric hindrance. The superior promoting effect of 4,7‐dihydroxy‐1,10‐phenanthroline is attributed to its water solubility under the basic conditions.

Water‐Soluble Ionic Palladium Complexes: Effect of Pendant Ionic Groups on Palladium Nanoparticles and Suzuki–Miyaura Reaction in Neat Water

“…[17] Inspired by the excellent catalytic performances of palladium NPs stabilized by ionic nitrogen-containing ligands, we speculated that the pendant linkers between the ionic group and coordination group probably have an important effect on the NPs owing to the difference in their structure and solubility in water. As a continuation of our research on catalytic reactions in neat water, [17,18] herein, we report the synthesis of three water-soluble nitrogen-containing chelating ligands: (N,N,N-trimethyl-6-(dipyridin-2-ylamino)hexyl-1-ammonium bromide (L1), (N,N,N-tributyl-6-(dipyridin-2-ylamino)hexyl-1-ammonium bromide (L2), and (N,N,N-trimethyl-N-6-(dipyridin-2-ylamino)triethoxy-1-ammonium bromide (L3). Their palladium complexes are used as precursors for the formation of palladium NPs, and the effects of the pendant ionic groups on the properties of the NPs and their catalytic activity in the Suzuki-Miyaura cross-coupling reaction in neat water are investigated.…”

Development of Proton‐Responsive Catalysts

“…We established a novel catalyst design (i. e., proton‐responsive ligand) for CO 2 hydrogenation. In addition, the catalyst design was applied to various catalysis, in which were promoted by the proton‐responsive catalysts …”

N‐(4‐Thiazolylmethyl)Morpholine N‐Oxide as N,O‐Bidentate Ligand for Copper‐Catalyzed Ullmann‐Type N‐Arylation of Azoles/Amines with Aryl Halides

“…Thus many endeavors to achieve these challenges have been made by different research groups in recent years. In 2013, 4,7‐dihydroxy‐1,10‐phenanthroline was developed as a pH responsive ligand for copper(I)‐catalyzed coupling reaction of imidazoles with aryl bromides in water by Wang's group . Jain R. reported CuI/trans‐N,N’‐dimethylcyclohexane‐1,2‐diamine‐catalyzed N (1)‐arylation of protected histidine, providing access to design of peptide‐based drug containing N(1)‐aryl histidine blocks under microwave irradiation .…”