The Construction Of C(sp~3)-C(sp~3)and C(sp~3)-O Bonds Based On Photocatalysis And Photoelectrocatalysis

It is an important research direction in the field of chemistry to develop a green,low-consumption,environment-friendly,simple and mild synthesis strategy with visible light as energy.In this thesis,the application of visible-light-induced photocatalysis and photoelectrocatalysis in C（sp³）-H activation has been investigated.Based on the mechanism of homogeneous and heterogeneous photocatalysis,a green photocatalytic synthesis strategy is further proposed.The research contents are outlined as follows:1.Visible-light-induced alkylation of alkenes with aromatic 1,3-dicarbonylsA green and mild photocatalytic method for C-C bond formation between1,3-dicarbonyls and styrene derivatives was developed.A series of linear selective products were obtained in medium to good yields.Based on the results of control experimental and theoretical investigations,this photocatalytic reaction might proceed through radical process via single electron transfer.And the photocatalyst can participate in the redox quenching cycle as oxidant and reductant at the same time（Scheme 1）.2.Visible-light-inducedα-oxyamination of 1,3-dicarbonyls with TEMPO via a photo（electro）catalytic process applying DSSC anode or in DSSC systemA green and enviromentally friendly photoelectrocatalytic one-pot method was developed for theα-oxyamination between 1,3-dicarbonyls and TEMPO via a photo（electro）catalytic process using visible light as the energy source.The recovered DSSC anode（photocatalyst）could be used more than 8 times,at the same time,theα-oxyamination reaction proceeded in DSSC device might be involved in the photoelectrocatalysis process.Mechanistic studies establish that the reaction might undergo via both the visible-light-induced radical and the ionic reaction processes（Scheme 2）.3.Harnessing visible-light energy for unbiased organic photoelectrocatalysis:synthesis of N-bearing fused ringswe realize the conversion of visible light to electrical energy and the C-H activation by the synergistic catalytic effect of visible-light and photoelectric current.An atom-economical and environment-friendly self-biasing interfacial photo-electrocatalytic method for cascade C-H activation/cyclization is provided to construct N-containing fused ring compounds using m-Bi VO₄ film as a photoanode.There are obvious advantages of this transformation due to no external bias and small overpotential,saving electrical energy and avoiding excessive oxidation of malononitrile to achieve better chemical reactivity and selectivity.Meanwhile,the recovered photoanode can be used more than ten times（Scheme 3）.