Studies Towards The Total Synthesis Of Lycopodium Alkaloid Lycopladine D

The Lycopodium alkaloids are a large series of natural products with unique heterocyclic frameworks.So far,more than 300 Lycopodium alkaloids have been isolated and identified.Owing to their complex polycyclic skeletons and diverse biological activities,the total syntheses of these alkaloids have attracted broad attention from the synthetic community in recent years.The major part of this thesis is the synthetic studies toward s Lycopodium alkaloid Lycopladine D.In the first chapter,the classification and biosynthetic pathway of Lycopodium alkaloids was introduced.Then,the total syntheses of fawcettimine-type alkaloids were summarized and introduced detailly.In the second chapter,we finished the syntheses of(-)-4-epi-Lycopladine D in 13 steps.Based on our previous work,a more concise and efficient synthetic route was designed to furnish the key 6/9 spirocyclic intermediate.The novel and chemselective carbonyl-olefin metathesis was used to construct the 5 member ring skeleton.In the late-stage,the aminal moiety and lactone moiety of Lycopladine D were constructed by the one step reaction of deprotection,cyclization,and retro-Claisen reaction.At last,we finished the syntheses of(-)-4-epi-Lycopladine D.