Study On The Reaction Of Visible Light-Induced α-Diazo Sulfonium Reagent With Alkenes And Alkynes

Carbon atoms have the unique ability to bond four atoms and form stable tetravalent structures that are ubiquitous in nature.When the carbon center breaks chemical bonds,intermediates such as carbocations,carbanions,carbon radicals,and carbon carbene are produced.Very extensive research has also been done on these topics.Research progress has been slow since diethylmercury bisnitroacetate{Hg[C(=N2)CO2Et]2} was used to prepare free carboxy radicals[:C-CO2Et]precursors to react with alkyl olefins.Because the carbine carbon radical acts as a highly reactive intermediate with three bonding orbitals,the reaction selectivity cannot be controlled.Through the visible light-induced α-diazonium sulfonium reagent,the slow-release strategy achieved the control of the reactivity of carbine carbon radicals,and convergently synthesized dihydrofuran-type products,olefinic double-bond slip products,and 1,4-dicarbonyl-Z-alkenes.In chapter two,the convergent synthesis of aryl alkenes with nucleophile(TMSCN)and α-diazonium sulfonium reagents to synthesize 2,3-dihydrofuran-type products.A total of 78 2,3-dihydrofuran-type products were developed and characterized,and the structures and relative configurations of the products were determined by single crystal diffraction.Different kinds of electron substituents of the substrates,complex macromolecular olefin substrates and α-diazonium sulfonium reagents are well compatible under standard reaction conditions.2,3-Dihydrofuran containing 2,3-dihydrofuran was synthesized by a free carbine radical strategy.The mechanism of the reaction process was explored through the carbon isotope(12C/13C)effect experiment,the switch lamp experiment,the determination of the redox potential of the diazonium reagent by cyclic voltammetry,the fluorescence quenching experiment and the fluorescence quantum yield experiment.The reaction betweenα-diazonium sulfonium reagent and alkene undergoes a free cycloaddition of free carbine,and then the resulting cyclopropane undergoes a three-membered ring-opening rearrangement to finally generate 2,3-dihydrofuran-type products.The third chapter is about the coupling reaction of benzopolycyclic olefin with TMSCN and α-diazonium sulfonium reagents.A total of 30 substrates were expanded,and the product structure was determined by single crystal diffraction.Various types of substituent groups,benzopolycyclic olefin substrates and their effects on the reaction were investigated.Through the mechanism study,the difference and reason of the reaction type with ordinary aryl alkenes were found.The same reaction conditions all experienced free carbine free intermediates,but the products were greatly different due to the influence of the ring tension of the alkene substrate.The cyclopropane intermediate produced during the reaction also undergoes the cyclopropane ring-opening rearrangement reaction,but instead of forming a closed five-membered heterocycle,the benzo-polycycloalkene double-bond-slip cyanation product is formed.The third chapter explores the three-component coupling reaction of alkyne,α-diazosulfonium reagents and water to synthesize Z-1,4-dicarbonyl alkenes.In this reaction,water provides both oxygen and hydrogen in the product and the conditions are mild.Alkyne substrates have high universality and also have good compatibility and Z-form selectivity.The reaction can be scaled up using a continuous mobile phase photoreactor.Using cheap D2O,the reaction can yield deuterated alkenes with high deuteration rate(D-inc.=90～97%).In addition,1,4-dicarbonylalkenes can efficiently construct a series of polysubstituted(deuterated)heterocyclic compounds via one-step derivatization.