Study On The Addition And Cyclization Reactions Of Active Olefins

Efficient and elegant syntheses of complex organic molecules with multiple stereogenic centres or novel structures continue to be important in synthetic chemistry. As a continuing program to our group’s study in development of new synthetic method to synthesis novel structure, this thesis mainly centered on the following four chapters involving the addition and cyclization reaction for active olefins as the substrates.Chapter1:Olefin is one of the most significant synthon in organic synthesis, so this chapter introduces the nature of the active olefins, and briefly summarizes the related reactions from two aspects of olefins as nucleophiles and electrophiles.Chapter2:"Study on the aza-Morita-Baylis-Hilleman reaction of Allenoate with N-DPP imines catalized by the dithiophosphoric acid Li-salt". This chapter mainly introduces the aza-MBH reaction of allenoate additions to N-diphenyl phosphoryl imines catalyzed by dithiophosphoric acid metal-salt. The allene as a special kind of olefins has many novel reaction performance and so much attention has been paid to allene chemistry. About the reaction between allenoate and amine, most has focused on the cycloaddition reaction, only a few reports involved the addition reaction. Considering the characteristics of aza-MBH reaction, we firstly used the dithiophosphoric acid metal-salt as the catalyst, the tetrasubstituted allenes had been obtained through the one pot reaction. the diphenyl phosphoryl group had been found to be very effictive in activating the imines. In addition, the products contain fuctional groups that are amendable toward further transformations. According to the result of the reaction, we presented a proposed mechanism of the reaction.Chapter3:"Organocatalyzed formal [2+2] cycloaddition of2-vinyl pyrroles with α,β-unsaturated aldehydes". This chapter firstly reviewed the methods of synthesis of the cyclobutane derivatives in decades. As a continuing program of organocatalysis in our group, we want to develop a new method of organocatalyzed synthesis of substituted cyclobutane derivatives. The diphenylprolinol silyl ether can effectively activate the α,β-unsaturated aldehydes to form the electrophilic iminium intermediates. At the same time,2-vinyl pyrrole serves as masked nucleophilic trienamine, can give various reactive intermediates through the double bond rearrangement. Combining the natures of the two substrates, we have successfully developed an organocatalyzed [2+2] cycloaddition reaction to synthesize a series of chiral cyclobutane compounds.Chapter4:"Tandem [4+2]/[3+2] cycloaddition reaction of nitroalkenes with2-vinyl-pyrrole substrates". Tandem cycloadditions could give the fused or bridged ring structures. The tandem [4+2]/[3+2] cycloadditions of nitroalkenes is a typical example for this strategy. Although this reaction has been widely investigated, there are still some shortcomings in some aspects such as the substrate scope is relatively narrow and the method of asymmetric synthesis is limited. As a part of previous work, we introduced the2-vinyl pyrrole derivative to the tandem organocatalyzed [4+2]/[3+2] cycloaddition reaction, the nitroso acetals structures were succesfully synthesized.