Study On The Synthesis Of Benzofuran Compounds Through[4+1] Cyclization Reaction Involving O-Quinone Methides

Benzofuran compounds are an important class of oxygen-containing heterocycles,due to their prevalence in biologically active natural products,pharmaceuticals,and agricultural chemicals.They have attracted a large amount of attention from organic synthetic chemists,and there are many strategies for the construction of oxygen-containing heterocyclic frameworks.Among them,[4+1]cycloaddition reactions of o-QMs were recently achieved to generate benzofuran derivatives using different C1 units.Based on the property of o-QMs in cycloaddition reactions,in the present dissertation,two kinds of[4+1]cycloaddition strategies were established with high reaction efficiency.The abstracts for each one was listed as follows:1.A PPh₃-triggered tandem strategy for the efficient synthesis of valuable 2,3-disubstituted benzofuran derivatives from aryl or alkyl acyl chlorides and o-quinone methides has been developed.The tandem reaction includes phospha-Michael addition/acylation/intramolecular Wittig reaction sequences of o-QMs.This method features mild and simple reaction conditions,a broad substrate scope,good to high yields and srepresent the first example of noncarbon nucleophiles with o-QMs in[4+1]cycloaddition reaction.2.A new strategy for the synthesis of benzofuran from o-QMs and terminal alkynes via Cu-catalyzed coupling-cyclization has been developed.The reactions proceeded smoothly under mild conditions with wide functional group tolerance.This new method demonstrates potentials for the synthesis of 2,3-disubstituted benzofuran containing natural products and biologically active compounds.