Radical Reactions Involving Katritzky Salts For Construction Of C(sp~3)-C(sp~2) Bonds

C-C bonds is undoubtedly the basis for the organic compound skeletons.Therefore,the development of strategies for the constructing of C-C bonds has been widely studied.Katritzky salt,as an alkyl radical precursor,has been widely applied by deaminative methods for its simple production,easy availability and high stability.In my master’s period,I was mainly engaged in the research of using Katritzky salt as a radical precursor,which focused on the construction of C(sp3)-C(sp2)bonds.This thesis introduces my work from three aspects:(1)Radical alkylation of isocyanides with Katritzky salts via photoredox catalysisIn this section,an efficient and mild method was developed for the synthesis of 6-alkylated phenanthridines upon visible light irradiation.Katritzky pyridinium salts derived from abundant amino acids/peptides were used as radical precursors for the alkylation of isocyanobiphenyl species.The reaction displays an excellent functional group tolerance and a potential utility for peptide functionalization,allowing access to desired products in good to excellent yields.(2)Ni-Catalyzed deaminative hydroalkylation of internal alkynesIn this section,we introduce a regioselective cis-hydroalkylation of internal alkynes with readily prepared Katritzky pyridinium salts for the synthesis of trisubstituted alkenes under the action of nickel.This reaction is the first example of a metal-catalyzed hydroalkylation of an alkyne via C-N bond activation of an amine.A combination of a SET-initiated radical process and Ni-catalyzed alkylation could engage in the reaction.(3)meta-Selective aryl C-H bond alkylation with Katritzky saltIn this section,Ru catalyzed meta-selective direct alkylation of arenes with Katritzky pyridinium salts was developed.Various arenes bearing pyridyl,pyrimidyl,pyrazolyl,isoquinoline,purine directing groups were tolerated in this meta-selective alkylation.Cyclometalation with a ruthenium(Ⅱ)complex activates the substrate molecule and also is responsible for the meta-selectivity.