Asymmetric Total Synthesis Of(-)-Cladospolide B, Syntheses On Chloriolide And Isocladosporin

This dissertation described the asymmetric syntheses of natural products (-)-Cladospolide B, Chloriolide and Isocladosporin. It consisted of the following four parts:Chapter 1. Asymmetric total synthesis of natural product (-)-Cladospolide BThe work of other groups in synthsis of (-)-Cladospolide B was briefly introduced.The natural product (-)-Cladospolide B was synthesized in 14 steps from commerically available (S)-ethyl lactate and 1,5-pentanediol, in which Sharpless asymmetric dihydroxylation, Mitsunobu esterification, Ring closing metathesis were the key steps and two stereocenters were established facilely with highly selectivity.Chapter 2. Studies on asymmetric synthesis of natrual product ChloriolideThe work of other group in synthsis of Chloriolide was briefly introduced.Various synthetic strategies to synthesize Chloriolide were tested. Asymmetric synthesis of Chloriolid was performanced using three-componment Lichpin, Sharpless asymmetric epoxidation, CBS-reduction and Payne reactions as the key steps, in which the key intemediates were obtained. Further study on total synthesis of Chloriolide is ongoing.Chapter 3. Studies on asymmetric synthesis of natrual product IsocladosporinVarious synthetic strategies have been tested to synthesize Isocladosporin. The syn-disubstituted pyran was constructed by ring closure catalized by BiBr3. The key intermediate was obtained through three-compoment Lichpin reaction as the key step. Further study on total synthesis of Isocladosporin is ongoing.Chapter 4. Nazarov cyclization and the applications in natural products syntheses (review)The mechanism of Nazarov cyclization, factors influencing activity, control of torquoselectivity in conrotatory cyclization, function of acid, localizing the double bond in the product, interrupted Nazarov cyclization pathways, and its applications in total synthesis of natural products were briefly introduced.