【作者】 刘德刚；

【导师】 李瀛；

【作者基本信息】 兰州大学 ， 有机化学， 2008， 博士

【摘要】 本论文对天然产物（-）-Pederin的右片段Pedamide以及黄烷类天然产物Broussin和Demethylbroussin的不对称全合成进行了研究。共包括以下三个部分:一、天然Pederin类天然产物全合成研究进展（综述）本章简要介绍了Pederin类天然产物的分离以及生物活性。归纳总结了Pederin,Mycalamide以及Psymberin等Pederin类天然产物全合成过程中的片段划分方法。根据构筑各个片段基本骨架的反应类型,突出地分类介绍和评价了它们的合成,并且综述了Pederin类天然产物的全合成进展。其中Pederin的右片段Pedamide是合成Pederin的重要片段,被作为关键中间体应用于文献报道的所有Pederin的全合成中。本章对Pedamide的不对称合成进展进行了详细的描述。Pederin类天然产物的生物合成随着生物技术的发展也取得了一些突破。本章同时概述了Pederin类天然产物的生物合成进展。二、Pederin右片段Pedamide的不对称全合成本章简述了Pederin的结构特点,合成Pederin的基本策略。开展了外消旋的Pedamide和（-）-Benzylpedamide的全合成工作。以新戊二醇为起始原料,通过基于分子内的羟基与环氧的S_N2亲核取代构筑吡喃环的方法,经过17步反应完成了外消旋的Pedamide的合成。合成过程中的关键反应为Grignard反应,双羟化反应,质子酸催化的羟基与环氧的S_N2亲核取代成环反应。以新戊二醇为起始原料,通过以I₂诱导的杂环化反应构筑Pedamide中的吡喃环,完成了（-）-Benzylpedamide的不对称全合成。分别以14步反应和16步反应为（-）-Benzylpedamide提供两条不同的不对称全合成途径。合成过程中的关键反应为Brown不对称烯丙基化反应,底物控制的Lewis催化的不对称烯丙基化反应,I₂诱导的底物控制的不对称杂环化反应,Sharpless不对称双羟化反应。同时还探索了一条基于分子内的羟基与环氧的S_N2亲核取代构筑吡喃环的不对称合成Pedamide的路线。三、天然黄烷的不对称全合成研究简述了天然黄烷Broussin和Demethylbroussin的生物及药理活性。开展了天然黄烷Broussin和Demethylbroussin的不对称全合成研究。以2,4-二甲基苯甲醛和对羟基苯乙酮为起始原料经过9步反应分别完成了目标产物Broussin和Demethylbroussin的全合成。合成过程中的关键反应为Aldol缩合,CBS不对称还原,Mitsnobu反应等。在实验中发现,CBS不对称还原产生的手性醇的ee值＞85%,而在经过Mitsnobu反应后脱除保护基所得到的最终产物发生了消旋化。这些研究结果为黄烷类天然产物不对称全合成提供了一定的借鉴。本文完成了（±）-Pedamide的全合成,（-）-Pedamide的不对称全合成,以及两个黄烷类化合物Brousin和Demethylbroussin的全合成。共涉及中间体及合成目标化合物72个,其中30个为新化合物。新化合物的结构均经过波谱分析方法确定。更多还原

【Abstract】 Asymmetric total synthesis of pedamide,the right half of（-）-pederin was studied. And we made much attempts to asymmetrically synthesize two natural flavan like compounds,broussin and demethylbroussin in our paper.The paper mainly involved three parts.1.The developments of the study of the total synthesis of pederin like natural compounds（review）The separation and biologic activity of pederin like natural compounds were introduced.The basic blocks in the syntheses of pederin like compounds including pederin,mycalamide and psymberin were summarized.According to the reaction forming the skeleton in every block,the syntheses of the blocks were summarized. And the development of the study of the total syntheses of pederin like compounds was reviewed,pedamide,the main block in the synthesis of pederin,was applied as the key intermediate in all of the synthesis of pederin according to the literature. Development of asymmetric syntheses of pedamide was described in detail. Biosyntheses of pederin were developed along with biologic technology.And the biosynthetic methods of pederin like compounds were summarized.2.Stereoselectively formal syntheses of pedamide,the right half of（+）-pederinThe character of configuration and synthetic strategy of pederin was introduced briefly.Syntheses of racemic pedamide and（-）-benzylpedamide were studied. Firstly,starting from 2,2-dimethyl-1,3-propan-diol,synthesis of（±）-pedamide was finished in 17 steps.The pyran ring was formed in a S_N2 substitution of hydroxyl and epoxide.In the scheme,the key reactions were Grignard reaction, dihydroxylation,S_N2 substitution of hydroxyl and epoxide under acidic conditions and etc.Secondly,starting from 2,2-dimethyl-1,3-propan-diol,asymmetric syntheses of（-）-benzylpedamide were finished in a scheme with 14 steps and another scheme with 16 steps.The pyran rings were formed in an I₂-induced heterocyclization of hydroxyl and olefin.In the two schemes,the key reactions were Brown’s asymmetric allylation,substrate-controlled and Lewis acid-catalyzed asymmetric allylation,I₂-induced asymmetric heterocyclization and Sharpless asymmetric dihydroxylation.In addition,an asymmetric synthesis was investigated based on the S_N2 substitution of hydroxyl and epoxide intermolecular.3.Stereoselectively total syntheses of natural flavanThe biologic and pharmacologic activities of two flavans were introduced including broussin and demethylbroussin.Asymmetric syntheses of broussin and demethylbroussin were studied.Starting from 2,4-dihydroxy-benzaldehyde and 4-hydroxy-acetophenone,asymmetric syntheses of broussin and demethylbroussin were finished in two schemes,which were both in 14 steps.The key reaction included Aldol condensation,CBS asymmetric reduction and Mitsnobu reaction.In the experiment,ee value of the chiral alcohol formed in CBS asymmetric reduction was over 85%.The treatment of the chiral alcohol with Mitsnobu reaction followed by deprotection gave racemic product.But these experiences could be used for reference in the syntheses of flavan like compounds.In summary,（±） -pedamide and（-）-benzylpedamide were synthesized through short schemes.In addition,two natural flavans were synthesized including broussin and demethylbroussin.In our work,72 compounds were synthesized as the intermediate or target compounds.Among of them,35 compounds were new.The configurations of all the compounds were proved by NMR,MS spectrum and etc.更多还原