The Studies Of Cascade Annulations For The Synthesis Of Fused Pyridines,Pyridones,and Furans Based On Iminyl Radical-Triggered Hydrogen Atom Transfer

Heterocyclic compounds widely exist in organic molecules and functional materials.Thus,the development of concise and efficient synthetic methods for the construction of heterocyclic compounds has been one of the most active research fields.Although various methods towards the heterocyclic compounds have been successfully explored,it still is an urgent demand to facilitate the discovery of heterocyclic compounds in various fields.For instance,the study of radical chemistry has attracted much attention from chemists due to its reliable and efficient characteristics.The radical strategy has significantly improved the low chemo-or regioselectivities and poor reactivity,avoiding the use of precious transition metals and harsh conditions.The merits make the C-H functionalization by radical process becoming one of the frontier fileds in organic chemistry.In this dissertation,we introduced the radical-induced functionalization of C-H bonds.In addition,our work focusing on the radical reaction were deeply introduced and discussed.Part Ⅰ:Relay C–H functionalization enables de novo synthesis of pyridines and pyridonesIn this work,we describe an iron-catalyzed relay C–H functionalization protocol that enables de novo synthesis of a wide range of structurally new pyridines and pyridones using oxime esters and cyano-containing alkenes as the starting materials.This transformation involves three-fold C–H functionalization(two Csp~3–H and one Csp~2–H),and allows the simultaneous generation of three new bonds and two rings in one-step.The reaction features operational simplicity,good functional group compatibility and the suitability to derivation of some bioactive molecules.Various control and DFT investigations support an interesting imineα-carbon radical addition/1,5-hydrogen atom transfer/homolytic aromatic substitution cascade process.Part Ⅱ:Fe-catalyzed radical strategy for cascade annulations of 4-hydroxycoumarins and oxime esters:A novel synthesis of furo[3,2-c]-coumarinsIn this work,we describe an iron-catalyzed radical strategy for cascade annulations of 4-hydroxycoumarins and oxime esters for the construction of furo[3,2-c]-coumarins in one step.This strategy allows the simultaneous generation of two C-C bond and one C-O bond.The reactions feature good functional group tolerance,including halogen,olefin,ester groups,and some sterically hindered groups.