Studies Toward Total Syntheses Of Pentaketide Ansamycin Microansamycins A-C And Catellatolactams A And B

This thesis mainly describes the application of C-H bond insertion reaction in the field of natural products synthesis,and the efforts toward pentaketide ansamycin microansamycins A-C and catellatolactams A and B.The thesis consists of the following four chapters:Chapter 1 Applications of C-H bond insertion reaction in total synthesis of natural products（Review）The application of C-H bond insertion reaction in total synthesis of natural products in recent years was reviewed which has obvious advantages over traditional synthetic design in terms of step,atom,and redox economy.Then the review was divided into two categories based on the transition metal catalysis with more detailed explanation,which provided an important background for the follow-up research work.Chapter 2 Studies toward the pentaketide ansamycin Microansamycins A-CThis chapter briefly introduces the isolation and synthesis background of pentaketide ansamycin microansamycins A-C.Five strategies were designed to construct the skeleton of pentaketide ansamycin microansamycins A-C,including ketene-trapping,ring-closing metathesis,intramolecular Sm I₂-mediated Reformatsky reaction,oxidative coupling and regioselectivity C-H insertion reaction.In addition,the biogenesis of these natural products were also explored.Chapter 3 Total syntheses of Catellatolactams A and BWe have developed a divergent approach to achieve the first total syntheses of the novel pentaketide ansamacrolactam natural products catellatolactams A（287 mg）and B（205 mg）in 5 and 8 steps,respectively.The key reactions of our synthesis included condensation of the acylated Meldrum’s acid and aryl amine,a regioselectivity C-H insertion reaction to construct theγ-lactam moiety,and an RCM reaction to forge the macrocycles with E-olefin in the strained 13-membered lactam and 10-membered carbon ring.This synthesis gives access to the large quantity of catellatolactams A and B and provides a general,concise,and scalable synthetic strategy for synthesis of other relevant compounds for biological studies.Chapter 4 Summaries of this thesis...