| Aldehyde enolate is a kind of intermediates with special structure features,and could participate in many enolizable aldehyde-involved catalytic asymmetric transformations.The study on the generation,geometric isomerization,counter cation,stability,reactivity and selectivity control of aldehyde enolate may help to develop new aldehyde-involved asymmetric transformations and synthesis of complex chiral targets.In this thesis,we studied the inverse-electron-demand hetero-Diels-Alder reactions involving aldehyde enolate intermediates,including the aza-Diels-Alder reactions and oxo-Diels-Alder reactions,and achieved the efficient synthesis of tetrahydropyridine derivatives and dihydropyranone derivatives with a methyl quaternary carbon center.The main contents of this thesis are as follows:1.The nucleophilic activation modes of aldehydes are briefly introduced,including covalent activation(enamine activation,SOMO activation,carbene activation etc.)and noncovalent activation(Br(?)nsted base activation,Br(?)nsted acid activation,phase transfer activation etc.).Then the recent progress in of catalytically in situ generated aldehyde enolate-involved tandem and cyclization reactions was reviewed.Finally,based on the description of the inverse-electron-demand hetero-Diels-Alder reaction,the research plan and content of this thesis are introduced(catalytically in situ generated aldehyde enolate-involved inverse-electron-demand hetero-Diels-Alder reaction).2.A series of substituted tetrahydropyridine was synthesized by using a tertiary amine catalyst through the aldehyde-enolate involved inverse-electron-demand aza-Diels-Alder reaction between unsaturated imines and enolizable aldehydes.Firstly,the catalyst was screened with mode substrate and the optimal reaction conditions were obtained.Subsequently,the scope of substrates for the reaction was studied,and it was found that the reaction was general and tetrahydropyridine derivatives were obtained in moderate to good yields.The relative configuration of the product was determined by X-ray single crystal diffraction analysis.Finally,the synthetic elaboration of the tetrahydropyridine derivatives was investigated.3.Using a quinine-derived bifunctional tertiary amine-thiourea chiral catalyst,the catalytic asymmetric inverse-electron-demand oxo-Diels-Alder reaction of unsaturated ketoesters and methyl phenylacetaldehydes was achieved via a disubstituted aldehyde enolate intermediate in moderate yields,a series of chiral dihydropyranone derivatives containing methyl-substituted quaternary carbon centers were prepared with high enantioselectivity and high efficiency.Firstly,the model substrate was used to screen the catalyst and other reaction parameters,and the optimal reaction conditions were obtained.After that,the reaction was found to have good substrate scope by investigating the generality of the reaction.This study provides an efficient and green method for the catalytic asymmetric synthesis of 3,4-dihydropyranone derivatives with a methyl substituted quaternary carbon center. |
