Polymer-supported N-heterocyclic Carbene-rhodium Complex Catalyst For The Addition Of Arylboronic Acids To Aldehydes

Although there have been many successful demonstrations of homogeneous catalysis using N-heterocylic carbene (NHC) as ligand for transition metals, heterogenous systems still remain practically useful catalysts. These catalysts can prevent the contamination of the ligand residue in the products. Due to their versatile processing capabilities and ease of separation and recycling, polymer-supported catalysts offer many advantages for industrial applications.These trends of heterogeneous catalysis inspired us to design a novel polymer-supported NHC ligand that can form effective complexes with Rh. A novel polymer-supported imidazolium salt was prepared from chloromethyl polystyrene (CM PS) resin using a simple procedure, and was used as a ligand precursor for rhodium (Rh) catalyst. Their properties were measured by elementary analysis and inductively coupled plasma-atomic emission spectrometry (ICP-AES).Transition-metal catalyzed addition of aryl groups to a carbon-heteroatom double bond is a versatile and highly useful transformation, which yield a wide variety of organic compounds. We turned our attention to the addition of arylboronic acids to aldehydes giving secondary alcohols, which can be promoted by NHC-Rh complex. We successfully applied the polymer-supported NHC-Rh complex to the...