Studies On The Total Synthesis Of Several Polycyclic Alkaloids

This paper reviews the research progress of the total synthesis of Galanthamine alkaloids and some Hasubanan-type alkaloids,and studies the total synthesis of several polycyclic alkaloids,which are mainly divided into the following three parts.Chapter 1:Progress in the total synthesis of Galanthamine alkaloidsGalanthamine is a phenanthridine alkaloid isolated from the Lycoris radiata plant in the Caucasus.It is mainly used for the treatment of myasthenia gravis,progressive muscular dystrophy,sequelae of polio,cerebral palsy in children,sensory or movement disorders due to neurological disorders,polyneuritis and other diseases.This section summarizes the biomimetic synthesis of Galanthamine and the synthesis after 1999.In these synthesis,different methods are used as the key reaction steps.The key reaction types are:(1)Method of oxidized phenol coupling;(2)Intramolecular Heck reaction;(3)Palladium-catalyzed asymmetric allyl alkylation method;(4)Semipinacol rearrangement;(5)Double Michael-Claisen series reaction;(6)Diels-Alder reaction;(7)Johnson-Clai sen rearrangement method to construct quaternary carbon;(8)Enantioselective Michael addition reaction;(9)Asymmetric catalytic hydrogenation reaction;(10)Palladium-catalyzed intramolecular Larock cyclization;(11)Cleavage of the C-C bond of benzocyclobutanoneChapter 2:Progress in the total synthesis of Hasubanan alkaloidsHasubanan-type alkaloids belong to the isoquinoline morphine-type alkaloids,which are mainly found in plants of the genus Stephania of the fangsaceae family,and more than 70 have been found.It's pharmacological activity is mainly manifested in anti-HBV,binding to opioid receptors,and anti-herpes simplex virus.In order to better develop and utilize lotus alkaloids,this section summarizes the structural characteristics and separation of 25 Hasubanan alkaloids.For the total synthesis of Hasubanan-type alkaloids is relatively small,we have selected some synthetic methods of alkaloids to introduce,such as Hasubanan-type alkaloids Cepharamine,Hasubanonine,Periglaucine B,Cepharatines A,C,and D,Isohasubanonine,Stephadiamine,etc.;Chapter 3:Synthesis of several polycyclic alkaloidsFor the synthesis of Hasubanan-type alkaloids Cepharamine and Metaphanine molecules,this paper is based on the palladium-catalyzed heck carbonyl intercalation tandem cyclization reaction to achieve the construction of a 6/5/6/6 tetracyclic framework.The subsequent 5-step reaction successfully obtained Ibuka's intermediate.The synthetic method known in the reference can complete the synthesis of the above two molecules.