Studies On The Transition-Metal-Catalyzed/Transition-Metal-Free Catalyzed/Radical Involved C-C Bond/C-Se Bond Cross-Coupling Reactions

Cross-coupling reaction is characterized by high efficiency,good selectivity and mild reaction conditions.It is an effective method for modern organic synthesis and one of the most common synthesis strategies for constructing carbon-carbon and carbon-heteroatom bonds.There are many kinds of reactions involved in the generalized cross-coupling reactions.This dissertation mainly introduces coupling reactions which have been favored by organic synthetic chemists in recent years.First,the great development of transition metal catalyzed cross-coupling reactions represents a great advance in organic synthesis methodology,and offers the possibility of constructing many new,unconventional chemical bonds.Secondly,with the emphasis on green,high efficiency and environmental protection,more and more researches have been carred out on the cross-coupling reaction without transition-metal catalysis.Meanwhile,with the vigorous development of radical chemistry in recent years,the previously challenging studies on C-H bond activation of saturated heterocyclic alkanes have been readily solved.The effective combination of radical chemistry and alkane activation has been widely studied.In this dissertation,the C-C bond and C-Se bond were successfully constructed based on above three cross-coupling reactions.Specific results are as follows:synthesis of pyridine aryl methanol derivatives by the construction of C-C bond via Ni-catalyzed cross-coupling reactions;synthesis of diaryl selenides by the construction of C-Se bond via transition-metal-free-catalyzed cross-coupling reaction;synthesis of alkylmethylamine derivatives by the functionalization of the C-H bond of saturated heterocycles via radical involved cross-coupling reaction.This dissertation is divided into five chapters.In the first chapter,three types of novel cross-coupling reactions were summarized,and their development status and research progress in the past five years were reviewed.In the second chapter,a efficient synthesis of pyridylaryl methanol derivatives via Ni/Ni Xantphos catalyst was developed.The chemically selective direct arylation and tandem arylation/[1,2]-Wittig rearrangement of pyridyl methyl ether can be effectively controlled by changing the reaction conditions.The reaction can tolerate a variety of aryl halides and the functional groups are well tolerated.The gram reaction has proved that it has good expandability,which will further expand and supplement the practicality of pyridyl methyl ether arylation.In the third chapter,synthesis of diaryl selenides by the construction of C-Se bond via transition-metal-free-catalyzed cross-coupling reaction between aryl benzyl selenoxides with phenols was developed,in the absence of traditional strong oxidants.The significance of this method is that it has provided a mild,fast,versatile and environmentally friendly way to construct a series of biologically valuable organoselenides.It has also avoided the difficulty of separating transition-metal impurities in the post-processing,while reducing the reaction cost and avoiding the sustainability challenge.This method maybe involve the mechanism of electrophilically substituted Se(IV)-Se(II)pathway,which reveals a new reaction possibility of organic selenium chemistry.In the fourth chapter,a unique transition metal free C(sp~3)-C(sp~3)dehydrogenation cross-coupling reaction between N-benzylimine and saturated heterocyclic ring has been achieved for the first time.The method used azaallyl anion as super electron donor(SED)and large hindrance aryl iodide as electron acceptor,which generated azaallyl radical and aryl radical by single electron transfer(SET).The latter further generated alkyl radical or benzyl radical by hydrogen atom transfer(HAT)with saturated heterocyclic ring or toluene derivative,and then formed new C-C bond by radical-radical coupling reaction with azaally radical.The direct functional group of saturated heterocyclic or toluene derivative C(sp~3)-H bond was achieved,and a series of alkyl methyl amine derivatives with medicinal value were obtained.In the last chapter,the research work of the dissertation was summarized,and the future investigation direction was suggested.