Photocatalytic Radical Cascades For The Construction Of Functionalized Dihydrobenzofurans

Dihydrobenzofurans are common component of drug and widely exist in the natural product structure.In addition,they also play an important role in organic synthesis as necessary intermediates.Therefore,dihydrobenzofurans have great value in synthesis.There are some limitations about synthesizing dihydrobenzofurans in literatures.Generally,multi-step synthesis of starting materials,relatively complicated harsh reaction conditions and the use of highly toxic reagents are required,which limited their application.Developing efficient methods to synthesize benzodihydrofurans under mild reaction conditions is still drawn intense attentions.Therefore,there were certain significance for theoretical research and industrial application.In recent years,organic photocatalytic radical cyclization has received considerable attention from researchers because of its relatively mild reaction conditions and good functional group tolerance.Herein,we reported organophotocatalytic radical cyclization reaction with aromatic amine as the substrates.The summery were as following:Part one:through photocatalysis,allyloxyaniline compounds produced efficiently benzoquinone-substituted benzodihydrofuran compounds.With the optimized conditions,we have explored the substrate scope and researched the reaction mechanism.This method has the following advantages:catalytic amount of organic photocatalyst,easy-operation,mild conditions and readily available substrate-sources which made the current methodology particularly interesting for synthesis.Part two:P,P-difluorocarbonyl-substituted benzodihydrofurans were generated with allyloxy aryl diazonium salts as the starting materials under sustainable conditions.Under the optimal reaction condition,the substrate scope was expanded and a series of mechanistic experiments were carried out to study the reaction mechanism,such as radical-trapping experiment,calculation of apparent quantum yield.On the basis of the above experiments and literature survey,we depicted a putative reaction cycles.This method has the following advantages:catalytic amount of organic photocatalyst,easy-operation,mild conditions and readily available substrate-sources which made the current methodology particularly interesting for synthesis.