Research On Selective Multihalogenation Of Unsaturated Hydrocarbons Regulated By Nitrogen Oxides

Organic halides have a wide range of applications in the fields of drug,materials and pesticides.In this present work,we highlight three keypoints: 1.It cannot be overstressed how fundamental roles of organic halides were played in organic synthesis.Organic halides are considered valuable building blocks in transition metal catalyzed cross-coupling reaction.2.Organic halides are widely present in the stuctures of natural products,material and pesticide molecules.3.The introduction of halides into organic molecules can significantly change the physical and chemical properties of compounds,especially in the field of drug synthesis.For instance,the incorporation of fluorine atoms into drug molecules can change the acidity and metabolic stability of target molecules.Conclusively,there is no doubt that exploiting new halogentation methods basing on easy available industry feedstock would have a profound effect on the whole organic community.This work mainly focuses on the halogenation reaction of unsaturated hydrocarbons,including the dehalogenation reaction of unsaturated hydrocarbons controlled by TEMPO and the selective halogenation reaction of terminal alkynes controlled by NMMO.Both of these methods use simple and easily available nitrogen oxides as additives to realize multiple halogenation modes of unsaturated hydrocarbons.This article mainly includes the following three parts.In Chapter 1,it mainly expounds how important role of organic halides in organic synthesis,and summarizes the methods of construcing C-X bonds with unsaturated hydrocarbons.Most of them were suffered with limited substrate scope and hazard conditions.Furthermore,these reactions usually were companied with some regio-and stereoisomers,which might raise several painstaking troubles for purification and application.In Chapter 2,we developed a simple and efficient dehalogenation reaction of unsaturated hydrocarbons.A TEMPO catalyzed cross-dihalogenation reaction was established via using electrophilic X+ reagent,such as NXS,DCDMH,DBDMH and TCCA.This reaction system tolerated a wide spectrum of functionalities and was amenable to gram-scale synthesis.With its mild conditions and operational simplicity,this method could enable wide applications in organic synthesis,which was exemplified by divergent synthesis of two pharmaceuticals.In Chapter 3,we described an selective halogenation of terminal alkynes by introducing4-methylmorpholine N-oxide.We can selectively obtain 1-bromoalkynes and tribromoethylene products by adjusting the amount of 4-methylmorpholine N-oxide and Nbromosuccinimide.The reaction exhibited high functional groups tolerance and even can be achieved in an ambient atmosphere.