Synthesis Of NHCs And Studies On Preparing Aminoboronic Esters

In the twentieth century, most chemical theoretical research focused on the covalentsynthesis and design. For organic chemists, the synthesis of organic compounds has beenone of the most important parts in their study. As we all know, the aromatic aminestructures exist in natural products, pharmaceuticals, chemical products, special electronicmaterials and mechanical materials. Although there are a lot of synthetic methods ofaromatic amines, the most commonly used methods have their limitations. Therefore, thedevelopment of new methods of carbon-nitrogen coupling reaction is significant. Thecoupling reaction has been the key point of research in organic synthesis for a long time,the coupling of carbon and nitrogen is widely used in the preparation of various drugs andintermediates. Aza-carbene ligands have always been important, and they play importantroles in organocatalysis, in particular, it has an irreplaceable position in organometallicchemistry. For the benzimidazole N-heterocyclic carbenes, C-N coupling reaction is thekey step in the synthesis. Therefore, the development of effective method for C-N couplingreaction must have a positive role in promoting for the synthesis and applications ofimidazole ligands. This study can promote further research of synthesis of amino boronicacids and preparation of drugs of amino boronic acids type based on N-heterocycliccarbenes. As coupling Reaction is one of the most important reactions in organic chemistry,there are lots of achievements on it. However, it has not been reported in detail on selectivecoupling reactions between primary amine and secondary amine. Through the studies ofthe selectivity, we can not only expand the breadth of the coupling reaction, but alsoprepare a lot of N-heterocyclic carbenes on the basis of the intermediates that aresynthesized using the new coupling method.Amino boronic acid compounds, as important pharmaceutical intermediates, havebeen lack of green and efficient synthetic methods. It is the most efficient catalytic systemfor the synthesis of the aminoboronic acid catalyzed by N-heterocyclic carbenes. However,the number of carbene ligand species is limited, there is still much space to optimize thereaction. We synthesized various N-heterocyclic carbenes and studied the influence of theelectrical and structural differences in the construction of amino acid, and explored a green and efficient method for the synthesis of the aminoboronic acid. An advanced and efficientCu-NHC complexe has been found, and a great breakthrough has also been made in themetal-free catalysis. This is significant for the borohydride reaction and the efficientsynthesis of the aminoboronic acid.