Studies On The Enantioselective Construction Of Quaternary Carbon Stereocenters In Aizoaceae Alkaloids

The synthesis of natural Aizoaceae alkaloids has received great attention because of their good biological activities, motivating researchers designed different ways for the fabrication of such kind of alkaloids. However, the asymmetric syntheses were rarely reported, and almost all of those limited asymmetric syntheses ways were dependent on chiral substrates or auxiliaries. The key innovation of the research is try to develop an stereocontrolled strategy for construction of the chiral quaternary carbon center using achiral substrates in asymmetric catalytic manner. In view of the above analysis, this study focuses on the following three parts:Part I:The asymmetric synthesis progress of Aizoaceae alkaloid (-)-Mesembrine has been re-viewed since 1971. In general, almost all of those limited asymmetric syntheses ways were dependent on chiral substrates or auxiliaries.Part II:(1) According to retrosynthetic analysis of the Aizoaceae alkaloid (-)-Mesembrine, the organocatalyst asymmetric Michael addition has been identified as a key reaction for building of chi-ral quaternary carbon stereocenters. And the progress of the organocatalyst asymmetric Michael addi-tion has been introduced briefly. (2) The chiral 1,2-cyclohexanediamine derivatives and cinchona de-rivatives were synthesised, and used to induce asymmetric Michael addition reaction. As a result, whether cinchona itself or their derivatives were superior than chiral 1,2-cyclohexanediamine deriva-tives. (3) An various solvents, and Michael acceptors were investigated in order to optimize the reac-tion condition. The results showed that chloroform as solvent,4g as catalyst,2c as acceptor was the best condition and good result was obtained (97.0% yield,-60% ee). (4) Moreover, the possibly cata-lytic mechanism of cinchona derivatives 4g is given. (5) The solid acid was prepared based on the polystyrene as the carrier and its acidity and structure properties have been characterized, subsequent-ly, its catalytic performance and recycling were inspected. It turned out that the 69% yield was still obtained after using ten times. And this study will lay a good foundation for synthesis of the target product.Part Ⅲ:The experimental details and spectroscopy data of the Michael donors, Michael accep-tors, and catalysts were afforded. All spectroscopy data and stereo-selectivity data of the Michael ad-dition were also provided.