Visible-Light-Promoted Decarbonylation,Acetalation And Ether C-H Bonds Reaction From Aldehydes

As above mentioned structure units,which are widely applied in organic synthesis,so there are a large variety of protocols to employ aldehydes to carry out photocatalysis reactions.Generally,there are many advantages such as raw materials and low cost.These cheap,commerical,and high-active aldehydes as the raw material.In addition,both low-cost Eosin Y or Ti O₂-MOF as precatalyst,which are easy to achieve and prepare,even Ti O₂-MOF as a recycled photocatalyst.Under transition-metal-free conditions via 455 nm blue LED（36W）,decarbonylative coupling of aldehydes with arenes,efficient acetalization of aldehydes with alcohols,and C（sp³）-H dehydrogenation coupling reactions with aldehydes can be accomplished efficiently with good functional group tolerance in good to excellent yield.The specific contents are as follows:（1）In this thesis,it is proposed that the decarbonylation reaction of aldehydes can be realized relatively simply without transition metal catalyst,high pressure or solvent.This efficientl strategy to synthesize biphenyl compounds in one step,and the experimental mechanism was confirmed by density functional theoretical calculation（DFT）.Moreover,This simple method proceeded with high functional-group tolerance such as previously unsuccessful 4-pyridine,-NO₂ and-SO₂Me,but offered a suitable catalytic system to aliphatic aldehydes for the first time.This novel synthetic method would be applied to the industrial production,providing high yields at low cost and being environmentally friendly.（2）Acetalas can be applied to protect carbonyl groups,it is necessary to introduce acetals and acetals to protect the carbon-oxygen double bonds of aldehydes or ketones.Recently,various useful and unique organic reactions via visible light have developed broadly.However,the reusability and chemselectivity of these catalysts are unsatisfactory.Hence,further development to photocatalysis is needed,and the synthesis of heterogeneous photocatalysts in acetals and ketals has been rarely reported.Based on the work of our group in photocatalysis,a green and inexpensive Ti O₂-MOF photocatalyst was developed to realize the acetal reaction of aldehyde,and successfully demonstrated the reusability of the catalyst,which is expected to be used in industrial applications in future.（3）In this thesis,the combination of catalytic Eosin Y and the TBHP of the equivalent amount promoted the C-H activation of the methoxyl group of benzo ether under nitrogen atmosphere.This method is suitable to both aromatic and aliphatic aldehydes,and has the advantages of wide substrate universality and low catalytic costs,which will providing a new route in industrial synthesis.