Study On The Application Of Pd(Ⅱ)-Catalyzed 1,2-/1,4-Nucleophilic Addition Of Arylboronic Acids In The Construction Of Quaternary Carbon Centers

Quaternary carbon centers are widely present in natural products,drugs,and biologically active molecular frameworks.Therefore,efficient construction of the quaternary carbon centers is one of the hot topics by chemists,and it’s always been prosperous.Many methods have been developed for the construction of quaternary carbon centers,including coupling reactions,addition reactions,rearrangement reactions,etc.Among them,the additions of nucleophiles toα,β-unsaturated ketones or imines are more mature methods.Compared with non-metal catalyzed reactions,metal-catalyzed reactions have the advantages of good functional group compatibility and high reactivity.Since organoboron reagents are a kind of good nucleophilic reagents not sensitive to air and water,they can participate in various addition reactions.In recent years,there have been numerous reports on metal-catalyzed addition reactions of aryl boronic acids for the construction of quaternary carbon centers.However,there are relatively few examples about Pd（II）-catalyzed 1,2-/1,4-addition reactions of arylboronic acids for constructing quaternary carbon centers,especially asymmetric versions.In this thesis,aryl boronic acids are used as the key substrates,which respectively react with different electrophiles such as yne-allenones or cyclic imines under the catalysis of Pd（II）and used to produce102 compounds containing ring quaternary carbon centers such as cyclobuta[a]naphthalen-4（2H）-ones,benzo[d]thiazoles and othes,thereby expanding the application of 1,2-/1,4-addition of arylboronic acids in the construction of quaternary carbon centers.This thesis is mainly divided into the following five parts:The first part mainly summarizes the recent research progess of yne-allenone-involved reactions and the research background of 1,2-/1,4-addition reactions of aryl boronic acids.The second part reports a selective Pd-catalyzed 1,4-addition reaction of aryl boronic acids to yne-allenones.With Pd（II）catalyst and 1,10-phenanthroline as the co-catalytic system,and DCE as the solvent,the reaction between yne-allenones and arylboronic acids worked readily,enabling[2+2]cycloaddition and 1,4-addition relay to give cyclobuta[a]naphthalen-4（2H）-ones containing all-carbon stereocenters in generally high yields.Considering ring tension of the four-membered ring from cyclobuteno[a]naphthone and its easy ring-opening,these resulting cyclobuta[a]naphthalen-4（2H）-ones were reacted with various alcohols by using Lewis acid catalyst,which underwent selective ring-opening to provide 32 examples of alkoxynaphthalenes bearing a terminal olefin unit in 52-98%yields.Interestingly,alkoxynaphthalenes could further undergo intramolecular cyclization in the presence of HBF₄,delivering 12 examples of benzo[a]fluorenes with an all-carbon stereocenter in 51-84%yields.In view of the literature reports and the above experimental results,three reasonable mechanisms for these three products were proposed.The third part reports the Pd（II）-catalyzed asymmetric 1,2-addition reaction of arylboronic acids and cyclic imines.Using Pd（II）and the preformed N-sulfonyl bisimidazole chiral ligands as an asymmetric catalytic system,the reaction of arylboronic acids with cyclic imines including benzo[d]isothiazole-1,1-dioxides,benzo[e][1,2,3]oxthiazine-2,2-dioxides and 1,2,5-thiadiazole-1,1-dioxides proceeded readily,prodvding a series of heterocycles containing quaternary aminocarbon centers undergo with high yields and excellent enantioselectivity（>99%ee）.The combination of the preformed chiral N,N’-bissulfonyl bisimidazole ligand with Pd（II）salts show outstaading catalytic performances to realize the asymmetric effective construction of quaternary aminocarbon centers and further expand the application this catalytic system.This reaction system could be carried out without nitrogen protection,which makes the workup easy,and provides an effective method for the construction of enantioenriched cyclic stereoscopic aminocarbon centers.The fourth part belongs to the experimental part,in which the synthestic methods for above compounds were described in detail.The fifth part includes the characterization data of all compounds.In brief,in this thesis,by using Pd-catalyzed 1,2-and 1,4-addition reactions of arylboronic acids,102 examples of quaternary carbon center-containing cyclobuta[a]naphthalen-4（2H）-ones,benzo[a]fluorenes and benzo[d]thiazoles were synthesized were synthesized,in which the structures of some products were confirmed by single crystal X-ray diffraction analyses.