The Research Of [4+3]/[4+1] Cycloaddition Involving Ortho-hydroxyphenyl-substituted Para-quinone Methides

Oxygen-containing heterocycles widely exist in many active natural products and drug molecules which have been used in the fields of life science,material science.In the past several years,the utilization of para-Quinone Methides as the key intermediate to construct oxygen-heterocyclic compounds through cycloaddition reactions has been developed.In this thesis,recent advances in this research area were reviewed in detail and the related application of para-Quinone Methides towards the synthesis of benzo[1,4]oxazepine and 2,3-dihydrobenzofuran derivatives were investigated.The detail of works is listed as below:Firstly,a formal metal-free and base promoted[4+3]-cycloaddition reaction of para-Quinone Methides with in-situ generated azaoxyallyl cations was reproted.Under the condition of K₂CO₃and CH₃CN,benzo[1,4]oxazepine derivatives can be obtained in good to excellent yields（up to 91%）.It was noted that successful embedding several natural isolated in target products with good yields and diastereoselectivity,efficient synthetic transformations of final benzo[1,4]oxazepine products further demonstrated the potential application of the strategy.Based on this investigation,we further realized a combination of visible-light promotion and cycloaddition process involving para-Quinone Methides.It was found that the carbene from aryl diazoacetate severing as C1 synthon can participate in[4+1]-cycloaddition with para-Quinone Methides to construct 2,3-dihydrobenzofuran derivatives.This one-pot,two-steps reaction mainly contains O-H insertion/cyclization process.Finally,we also successfully carried on some transformations of final products,which renders this approach attractive and valuable.