Direct Functionalization Of Nitrogen-containing Heterocycles Is Achieved By Free-radical Methods

Heterocyclic compounds,as an important component of drug molecules,natural products and biologically active molecules,have long been concerned by chemists.The direct functional group modification of heterocycles has also been one of the hot topics of chemists' attention.The radical reaction is often highly reactive and can significantly reduce reaction time,making it a powerful tool for chemists to build chemical bonds.In addition,the recent boom in radical chemistry has given a new impetus to radical-based approaches to heterocyclic functionalization.Therefore,based on the radical approach,we have selected some representative heterocyclic skeletal structures to explore their reactivity at different sites and modify them with reactive functional groups.Chapter 1The recent researches on the functionalization of heterocycles were summarized from two perspectives: the forming of C-C bonds in heterocycles and the construction of C-X(X=Si,N,P,S)bonds.Chapter 2A method for the oxidative cross-dehydrogenative coupling of imidazopyridines with silanes using di-tert-butyl peroxides as oxidants is developed.the coordination of Lewis acids is the main factor controlling the selective addition of the silyl radical region to imidazopyridines.At the same time,the reactions have a wide range of substrate suitability,yielding the corresponding C-5 position silylated imidazo[1,2-a]pyridine derivatives in moderate to high yields.Chapter 3We have successfully achieved ?-amino alkylation of electron-deficient heterocycles by the decarboxylation of ?-amino acid acids.The visible light photoredox catalysis under air provides a mild reaction condition.Therefore,numerous natural and unnatural amino acids,including peptides and drug molecules,are compatible in the system.This reaction offers a new method for the coupling of two important biologically active structure motifs.