Studies Toward The Photocatalytic Nitrogen Radical Cascade Reaction And Application In Total Synthesis Of Corynanthe Alkaloids And Cinchonidine

This thesis mainly describes the photocatalytic nitrogen radical cascade reaction and its application in the total synthesis of natural products.The paper consists three parts.The first part introduces the research progress of nitrogen radical chemistry and the establishment of photocatalytic nitrogen radical cascade reaction methodology.The second and third part are the application of the nitrogen radical cascade reaction discovered above to carry out the total synthesis study of corynanthe alkaloids and cinchonidine.Compared with the booming carbon free radicals,the study and application of nitrogen radicals are very young,mainly because the nitrogen radicals are less active and lack of efficient and reliable generating pathway,so it was neglected in the early age,only in the last few decades that nitrogen radical chemistry has made some progress.With the development of nitrogen radicals,the methodology shows great potential in the synthesis of heterocyclic compounds.It can not only be used as an active intermediate,but also can realize heterocyclic synthesis.It's suitable for constructing complex polycyclic systems containing nitrogen.In view of the many advantages of nitrogen radicals,we have successfully developed nitrogen radical cascade reaction catalyzed by blue visible light which can effectively construct the core framework system of multiple type indole alkaloids with aniline derivatives protected by p-toluene sulfonyl(Ts)as the substrate.The reaction conditions are mild,the functional groups are well tolerated,and the scale up is robust.After the establishment of the above methodology,we explored its application in the total synthesis of corynanthe alkaloids and cinchona alkaloids.Using chiral monoester aldehyde as starting material,eight natural products and one natural product isomer were prepared by eleven to fourteen steps.Taking the same starting material and through seventeen steps,the cinchona alkaloid cinchonidine was completed,all of this proved the great advantage of the nitrogen radical cascade reaction methodology in the total synthesis of alkaloids.