New Reactivities Of Frustrated Lewis Pairs

Frustrated Lewis pairs(FLPs)has attracted considerable attention of chemists because of its unique chemical reactivities.In the past ten years,the discovery of FLPs has provided new ideas of reaction design in the fields of main group element chemistry in catalytic hydrogenation,small molecule activation and organic synthesis.During the exploration of this dissertation,some new reaction fashions that are different from the classic FLPs have been discovered,which may inject fresh blood to the traditional organic chemistry textbooks.This dissertation prepared many novel structures from two kinds of FLPs through the activation of a series of chemical bonds(single bond/triple bond).This dissertation consists of the following four chapters:In chapter 1,the discovery and reaction mechanism of FLPs are briefly described.The synthesis and reactivities of frustrated radical pairs(FRPs)that have been developed in recent years are reviewed in detail.The relating reactions are classified and FRP’s distinctive reactivities are summarized.In addition,this dissertation introduces two main reaction modes for FLPs activating alkynes,which are named as addition reaction and deprotonation reaction.In chapter 2,the synthesis of new FRPs and their activation of different types of chemical bonds were mainly studied.The synthesized three FRPs achieved the homolysis of the B-H bond by means of single electron transfer(SET)for the first time,from which a new oxygen-bridged geminal N/B FLPs was generated and explored at the same time.In addition,FRPs can also activate the O-H bond,and reduce water to release hydrogen through single electron reduction.In chapter 3,we focused on the FLPs’ relay activation of carbon-carbon triple bond and carbon-hydrogen bond to build cyclic compounds.By tuning the type of alkyne(terminal alkyne/internal alkyne)attached to the substrate,FLPs can controllably induce the carbon-carbon coupling reaction to generate indole-annulated seven/eight-membered ring products.This kind of reactions are efficient and have broad substrate scope.Seven/eight-membered medium ring compounds are not as stable as five/six-membered ring compounds due to strain.These discoveries provide new ideas for the construction of medium-ring compounds in synthetic chemistry.In this chapter,the reaction mechanism of these reactions was also explored and the key intermediate was isolated and characterized by single crystal X-ray diffraction.After further experiments,we found that the Zweifel-liked olefination reaction can remove the boron-containing group of seven-membered ring product and construct C-C bond without metal catalyst,which brought it wider range of applications.In chapter 4,the innovative points of this dissertation were mainly summarized.And the prospects were put forward for the following work at the same time.