Research On In-situ Generated Iodine-mediated Oxidative Reactions Of Alkenes

As the basic raw material of modern chemical industry, olefin has played an important role in the growth of the national economy and sustainable development of society. The reaction with functionalization of olefin has provided us with various products, which have been involved in people’s food, clothing, shelter, transportation. Due to the significantly practical application value of this transformation, the study on functionalization of olefin is still one of the popular topics in organic chemistry. Numerous different characteristics catalytic reaction system has been reported, many kinds of functionalized organic compounds were synthesized through various methods with inexpensive olefins as raw materials. In recent years, since the guidance of green chemistry as well as the continued demand of society for new kinds of fine chemicals, the discovery of new and efficient functionalization reaction from easily available and environmentally friendly starting materials is still highly desirable.As a readily available and environmentally benign ionic salt, ammonium iodide can be converted into iodine, and hydrogen iodide under different reaction conditions. These features make it possess considerable potential in organic synthesis. However, the utilization of it in the organic synthesis has been rarely explored. In this context, the present dissertation is mainly focused on developing two new kinds of functionalization reaction of alkene under different reaction system with the mediation of ammonium iodide. The detail are summarized as following:(1) With NH4 I as the supporting electrolyte and graphite as the inert anode, a new and highly efficient electrochemical method of indirectly activated CO2 for the synthesis of cyclic carbonates, which features excellent regio- and stereroselectivity, exceptional functional-group tolerance, availability of starting materials, operational simplicity, scalable synthesis, and economy. Upon the synergistic action of halogen I2 and base NH3 electrochemically generated in-situ, cyclic carbonates could be obtained with great selectivity under mild conditions without using of hazardous oxidants and expensive catalysts or additives. The utilization of inert anode could not only successfully achieve this transformation but also avoid the consumption of the metal anode and tedious separationwork of products. More importantly, the supporting electrolyte in this reaction system not only act as conducting salt, but also participate in the electrochemical reactions, which could dramatically improve the atom economy of the reaction.(2) The stereospecific electrosynthesis of cyclic carbonates from 1,2-disubstituted olefins and CO2 was first investigated in an undivided cell with NH4 I as the supporting electrolyte and graphite as the inert anode. The detailed study indicated that supporting electrolytes not only affected the chemoselectivity of this reaction, but also had great effect on the stereoselectivity of the product. When NH4 I was used as the supporting electrolyte,(Z)-β-methyl styrene could be exclusively converted to cis-cyclic carbonate, while the electrolysis with NH4 Br as the supporting electrolyte gave a mixture of cis- and trans-cyclic carbonate in a ratio of 1:1.4 under the same conditions. Under the optimized conditions, a wide range of 1,2-disubstituted olefins could be smoothly transformed to stereospecific cyclic carbonates with retention of olefin stereochemistry in excellent yields.(3) A novel ammonium iodide-induced radical oxidative alkenylation toward the synthesis of vinyl methyl sulfones from alkenes, DMSO and water is described. The process proceeded smoothly under metal-free conditions with high stereoselectivity and good functional group tolerance. The reaction was revealed to proceed through a domino reaction of oxidation and elimination after the radical addition to alkenes. In addition, this procedure provided a new valuable method of generating methylthiyl radical(MeS·) with simply heating ammonium iodide and DMSO, which would provide a new reference for other study on free radical reactions.(4) A novel ammonium iodide-mediated oxysulfenylation of styrenes with DMSO and alcohols for the synthesis of β-alkoxy methylsulfides has been developed. The sulfenylating agents applied in the previous investigations mainly focused on aromatic sulfur. In contrast,the installation of alkyl sulfide into alkenes for the β-alkoxy sulfides has been rarely explored. While poor selectivity, expensive reagents and harsh reaction conditions are the drawbacks of these reactions. Thus, the present method remedied the deficiency of previous work on the oxysulfenylation of alkene.