Visible-light-promoted Transfer Hydrogenation And Hydroacylation Of Azobenzenes

Azobenzene and its derivatives have important applications in the fields of materials science,nonlinear optical devices and pharmaceuticals.In addition,azobenzenes are a class of important synthetic intermediates in organic synthesis.At present,the chemical reactions that azobenzene involved mostly use an azo moiety as a directing group to realize the ortho-C-H functionalization.However,the method for constructing new chemical bonds by addition transformation of N=N bond has rarely been reported.In recent years,the visible-light-promoted chemical reactions have achieved great breakthrough,and has rapidly developed into a practical and powerful method for organic synthesis.In this thesis,aiming the shortage of N=N bond addition transformation of azobenzenes and using visible light synthetic strategy,the visible-light-promoted transfer hydrogenation reaction and hydroacylation reactions azobenzenes have been studied.The contents mainly include the following two parts.（1）The transfer hydrogenation of azobenzenes promoted by visible light was studied,and the correspondingly new method was established.Upon visible-light irradiation and in the presence of diboron reagent（B₂pin₂）,the reactions proceeded smoothly in methanol at ambient temperature.A broad range of symmetric and unsymmetric azobenzenes with diverse functional groups have been reduced to the corresponding hydrazobenzenes with a yield of up to 96%.（2）The visible-light-promoted decarboxylative hydroacylation of azobenzenes withα-keto acids was studied,and the new method for visible-light-promoted hydroacylation of azobenzenes has been developed under catalyst-and additive-free conditions.The hydroacylation reactions proceeded smoothly under visible-light irradiation at room temperature.A wide range of azobenzenes andα-keto acids were well tolerated and afforded the hydroacylated products in high to excellent yields.