Visible-Light-Induced Halogenation From Inorganic Halide Salt

As a class of functional compounds,organohalogens exist widely in natural products,pharmaceuticals and foodstuffs.The physicochemical properties of organic compounds can be changed after halogenationand more biological activities can be observed.In literature many halogenation methods have been reported,but most of them uses stoichiometric amount of oxidants or pre-prepared halogenating reagents,which generates large quantities of waste.So there are still great challenges for constructing organohalogens with environmentally friendly and highly efficient methods.Hence,this dissertation presents a novel green approach towards oxychlorination,oxybromination and diiodination of alkynes,which consist of very simple and efficient reaction conditions.Part I.Oxyhalogenation of alkynes.Employing NaBr and LiCl as halogen sources,water as oxygen source,air as oxidant,we have developed a green method for constructing ?,?-dihaloketones catalyzed by visible light.Variety of functional groups are compatible in this reaction.The control experiments helped us to derive a reasonable mechanism.A short,green synthesis of an anticarcinogen Mitotane was also accomplished on the basis of this oxyhalogenation reaction.Part II.Diiodination of alkynes.We also developed a new method of converting alkynes into diiodoolefins using visible light catalysis with NaI as iodine source and air as oxidant.Avoiding chemical wastes and pollution,we used a very mild conditions which are also compatible with various substrates to generate 1,2-trans-diiodoolefins.