The Synthesis Of N-heterocyclic Carbenes And Their Applications In Catalysis Chemistry

Compared to traditional phosphine ligands, N-heterocyclic carbene ligand has the followingadvantages:(1) strong conjugation, aromatic, robust, and more stable in the air.(2) Strong σ-electronand weak π electron acceptor, easy to form carban-metal bond, and can accelerate the reaction in theactive center of the substrate and the oxidative addition of metal.(3) Eaay to modificate structures bychanging the connections on the N atom group, you can adjust the spatial structure and electronicligand effects.(4) Ligands are easily to be prepared and inexpensive. These advantages make theN-heterocyclic carbene ligands either as the metal coordination chemistry and organometalliccatalysis, or as a catalyst for the direct catalytic reactions of small molecules, have been widely used.To synthesis stable and high catalytic activity of N-heterocyclic carbene catalyst has importanttheoretical significance and practical value. Therefore, we chose to study N-heterocyclic carbene as anobject, by exploring different types of synthetic N-heterocyclic carbene precursors, and to study theirsubject and object recognition in catalysis and their applications.This paper focus on the design and synthesis of N-heterocyclic carbene ligands starting in metalcoordination chemistry and applications of small molecule catalysis to commence the study, expectedto expand its in biology, medicine, the application of supramolecular chemistry.This thesis consists of the following two parts:Part1: Synthesis of N-heterocyclic carbene and their catalysis study based on chiral BINOL-skeleton.Chiral binaphthyl skeleton structure as chiral molecules has attracted wide attention, in themolecular skeleton modification, asymmetric catalysis and main aspects of good object recognitionperformance. N-heterocyclic carbene because of its unique nature, with strong coordination andstrong (C-H)… A-hydrogen bonds, therefore the object in the catalytic chemistry and anionrecognition has been widely used. Therefore, the subject of design two kinds of chiralbinaphthol-based chiral monodentate N-heterocyclic carbene ligands: one is the binaphthol protectedphenolic hydroxyl methyl structures, and the other is the binaphthyl phenolic hydroxyl groupsunprotected structures. And tested both of the structures as initial asymmetric catalysis and applied aspects of host-guest recognition.Part2: Abnormal N-heterocyclic carbene catalyst precursor in the synthesis and application ofintramolecular aldehyde-nitrile cross-coupling reaction.Because of abnormal N-heterocyclic carbenes’ structures are different from the normal statecarbenes, therefore they also have different catalytic properties from other types of catalystperformance. We prepared two kinds of abnormal state of N-heterocyclic carbene catalyst precursor,and with other types of N-heterocyclic carbene catalyst comparison, in the intramolecular couplingreaction of aldehyde nitrile, under optimal conditions, product yield can be as high as97%.