Total Synthesis Of Erythrina Alkaloids(+)-2-epi-erythrinitol

The erythrina alkaloids,isolated from the genus Erythrina,have attracted interest because of their interesting structures and their range of useful biological activities.Some members of this family have curare-like activity,in addition to hypotensive,sedative,and CNS depressant properties.Erythrina alkaloids have characteristic polycyclic structures,and they have proven to be popular target molecules for synthetic chemists to exploit new methods for ring-forming reactions.Dearomatization reactions triggering cascade reactions provide quick access to core structure of complex natural products,which greatly improves the overall eff-iciency of a synthesis.In this paper,total synthesis of(+)-2-epi-erythrinitol was accomplished using dearomatization-asymmetric Michael addition reaction as the key step.This thesis consists of three chapter:In the first chapter,a review summarized the recent advance of dearomatization aeactions is presented and focused on catalytic asymmetric dearomatization aeactions mediated by transition metals and the total synthesis of erythrina alkaloids reported in recent years.In chapter 2,the dearomatization-asymmetric Michael addition reaction of para-amino phenol and total synthesis of(+)-2-epi-erythrinitol were studied.Three continuously chiral centers in high enantioselectivity were successfully established after many reaction conditions,such as catalysts,solvents,temperature,were screened and total synthesis of(+)-2-epi-erythrinitol was accomplished from the key intermediate.In chapter 3,experiment procedure and physical data for compounds described in Chapter 2 were recorded.In this thesis,phenolic compounds asymmetric dearomatization was studied,and the total synthesis of erythrina alkaloids(+)-2-epi-erythrinitol was achieved.Furthermore,on the basis of this thesis,it is expected to complete the total synthesis of 3-demethoxyerythratidinone through transforming the functional groups.