Study On Cycloadditions Of Vinylethylene Carbonates

Oxygen-containing heterocyclic constitutes a family of biologically and are a very important class of organic compounds.There heterocycles can be constructed via the cycloaddition reactions concisely and efficiently.Vinylethylene carbonates are important precursor compounds for the construction of multi-component oxygen-containing heterocyclic compounds.They have been widely used and have attracted wide attention of chemists.In this paper,we mainly explore the synthesis of five-and seven-membered oxygen-containing heterocyclic compounds by cycloaddition reaction using vinylethylene carbonate as a synthetic building block.It is hoped that the research and development of oxygen-containing heterocyclic compounds will be promoted.This thesis involves the following two parts:1.Synthesis of seven-membered lactones by [5+2] cycloaddition reaction of vinylethylene carbonates with oxazolonesThrough the model reaction of vinylethylene carbonates and oxazolones,various factors affecting the reaction were optimized,such as palladium catalysts,phosphine ligands,additives,solvents and temperature,and the optimal catalytic system was constructed.Under the optimal reaction conditions,the substrate was expanded by changing the structure of the substituents and functional groups of the reaction substrate.A total of 26 substrates were expanded,and the yield was up to 99%.A series of potentially biologically active seven-membered lactones were synthesized.The structure of the target compound was determined by X-ray single crystal diffraction,and the [5+2] cycloaddition reaction mechanism of vinylethylene carbonates with oxazolones was presumed.At the same time,the [5+2] asymmetric catalytic cycloaddition reaction of vinylethylene carbonates with oxazolones was investigated.The enantioselectivity of seven-membered lactone compounds could reach 39% through the screening of metal catalysis and organic small molecule catalysis.2.Synthesis of five-membered lactones by [3+2] cycloaddition reaction of vinylethylene carbonates with oxazolonesThrough the model reaction of vinylethylene carbonates with oxazolones,the factors affecting the reaction were optimized,such as palladium catalysts,achiral phosphine ligands and chiral phosphine ligands,five-membered lactones with potential biological activity were synthesized with excellent chemical yield(>99%)and low enantioselectivity(>3:2).The structure of the target compound was estimated based on hydrogen spectrum,carbon spectrum and mass spectrometry.Based on the structure of the proposed target compound,the [3+2] cycloaddition reaction mechanism of vinylethylene carbonates and oxazolones was investigated.