Construction Of New Spiro-/Bridged-Oxindoles And Fused Chromanes

Nitrogen-and oxygen-containing heterocycles are important structural units prevalent in natural products and drugs and exhibit significant bioactivities.As the representative of nitrogen heterocyclic compounds,spiro-/bridged-oxindoles are receiving more and more attention from organic chemists due to their diverse and complex structures and interesting bioactivities.In addition,fused chromanes are also biologically interesting moieties and much effort has been devoted to constructing them.Recently,many cascade reactions have been developed to construct mono-or bi-spirooxyindoles.However,protocols for the construction of bridged spirooxindoles are less explored.In the second chapter of this paper,the first highly diastereoselective Michael addition/condensation/Friedel-Crafts alkylation cascade reaction of 3-indolyl-substituted oxindoles with ortho-hydroxychalcones was established,which afforded a wide range of polycyclic indole-bridged chroman spirooxindoles with novel and complex scaffolds in moderate to excellent yields.Bispirooxindoles are endowed with more congested and complex architectures with two spiro quaternary carbon centers,which have posed great challenges to synthetic chemists.In the third chapter,an efficient three-component one-pot [3+2] cycloaddition of isatins,1,2,3,4-tetrahydroisoquinolines and methyleneindolinones has been developed.This reaction proceeded in a highly diastereoselective manner to afford a wide range of pyrrolo[1,2-a]isoquinoline-based bispirooxindoles in up to 91% yields.Fused chromanes are frequently encountered in natural products and pharmaceuticals and exhibit a wide spectrum of interesting biological activities.Consequently,the development of robust methods to access them has attracted considerable attention.In the fourth chapter,a multi-component one-pot cascade reaction of hydroxyketones with ortho-hydroxychalcones has been developed to afford an array of new fused chromanes compounds with complex molecular architectures.This reaction not only provides an expedient and convenient synthetic strategy to access complex fused chromanes but also establishes a new reaction mode of ortho-hydroxychalcones.