Synthesis Of Key Intermediates Of (-)-mesembrane And (-)-mesembrine

Sceletium alkaloids are apricot plants and they have obvious characteristics of alkaloids,such as regulation of emotional,anti-anxiety and stimulate the role of nerve center.(-)-mesembrane and(-)-mesembrine are representative molecules in the Sceletium alkaloid,they are the hot target molecules in the synthesis of natural products from the discovery of separation,as the same time it provides a solid foundation for the synthesis of Crinine alkaloids.The structure of(-)-mesembrane and(-)-mesembrine are relatively fixed,and their structures contain the cis-3a-aryloctahydroindole structure of(3aR,7aS).The construction of the quaternary carbon center is a key step in the synthesis of such molecules.In this paper,the target molecules were synthesized by three methods of constructing the carbon center,and the key quaternary carbon centers were synthesized by organic small molecule catalysts and metal palladium catalysts in order to complete the asymmetric synthesis of target molecules.In the first chapter,the development and classification of organic small molecule catalysts are introduced,it makes a brief introduction of L-proline-silicon ether based on amine catalysis,quinine amines based on enamine catalysis,quinine-thiourea based on hydrogen bonding.And then the development history of metal palladium catalysis and the five well-known reactions were introduced.The second chapter uses three methods to construct the quarterly carbon center to synthesize target molecules.Firstly,the key cyclic nitroene 92 is synthesized by two synthetic methods,and the intermediate was finally obtained at a yield of 70.4%.Then the quaternary carbon centers were constructed using three catalytic small molecular catalysts.And then the application of metal palladium catalyst to build a key quarter of carbon center,ultimately get 114,127,128 and other key intermediates,it provides a solid foundation for the synthesis of(-)-mesembrane and(-)-mesembrine.