Studies On The Construction And Transformation Of Carbon-Halogen Bonds

C-X(X = halogen)bonds exist ubiquitiously in organic molecules,and they are also the major functional groups in the contruction of C-C and C-heteroatom bonds,enabling them the irreplaceable applications in the synthesis of natural products,pharmaceuticals and materials.The researches reported of this thesis are new reactions involving C-H bond constructions and transformations.The contents consists mainly the C-H halogenation of the C-H bonds in quinoline ring,the halogenation based on enamione C-C double bond cleavage,copper-catalyzed tandem reactiosn initiated Ullmann C-S coupling and the palladium-catalyzed tandem reactions initatied by Suzuki coupling.In the first section,the selective C5,C7-dihalogenation and the C5-halogenation are reported.Using 8-hydroxyquinolines,benzoyl chlorides and N-halosuccinimide as substrates,the selective C5,C7-dihaogenated quinolines and C5-halogenated quinolines are selectively synthesized under different reaction conditions.In the second section,the ?-dihaloand trihaloacetophenone synthesis via C-C double bond cleavage of the tertiary enaminones is reported.Starting from the N,N-disubstituted tertiary enaminones and N-halogsuccinimide,the synthesis of ?,?-dihalogenated acetophenones and ?,?,?-trihalogenated acetophenones are synthesized in the presence of bisbenzoyl peroxide(BPO),respectively.In the third section,the tunable synthesis of 2,3-dihydrobenzothiazolones and benzisothiazolones via Ullmmann C-S coupling-based tandem reactions is reported.By employing starting materials of o-iodobenzamides,elemental sulfur and dichloromethane,the synthetic method for 2,3-dihydrobenzothiazolones is established with the copper catalysis and ligand assistance.On the other hand,without using dichloromethane,the selective synthesis of benzisothiazolones is accessed with the irradiation of microwave.In the fourth section,the palladium-catalyzed tandem Suzuki coupling and dichloromethane-based nucleophilic esterification reactions are reported.With o-iodobenzoic acids,boronic acids and dichloromethance substrates,the tandem reactions consisting Suzuki coupling and dichloromethane-based nucleophilic esterification is achived,which provides a synthetic method toward methylene-bridged bisiaryl carboxylates.