Design And Synthesis Of Novel Chiral Spirocyclic N-Heterocyclic Carbene Salts And Their Gold Complexes

Many chiral N-Heterocyclic Carbenes (HNCs) have been synthesized and used in transition-metal-catalyzed asymmetric reactions in past decades, which exhibit amazing enantioselectivity and reactivity. However, for some reactions. NHCs are not as effective as expected. The design of effective chiral NHCs. especially IMHCs having novel chiral backbones, is still an important task in the area of asymmetric catalysis. Spiro compounds, especially C2-symmetric spiranes have been proved as privileged structures and used in many remarkable ligands as basic backbone. In the past ten years, our group has developed various types of semipinacol reactions and tandem reactions to form spirocyclic compounds, and synthesized a vatiety of alkaloids and Pharmaceuticals based on these reactions. In this dissertation, the design and synthesis of novel chiral six-membered spirocyclic NHC salts and their NHC-Au complexes is described in the following three parts:1. The first charpter summarizes the preparation of spiro ligands and their application in asymmetric reactions.2. The second charpter briefly reviews the variety, structure, preparation and application of NHCs and NHC complexes.3. The last charpter investigates synthesis of four novel chiral six-membered spirocyclic NHC salts and three their NHC-Au complexes based on spiro[4.4]nonane.