【作者】 陈洁；

【导师】 曹小平；

【作者基本信息】 兰州大学 ， 有机化学， 2009， 博士

【摘要】 本论文主要研究海洋天然产物—malyngamides类的全合成,共分为四章:首先综述了近年来malyngamides类海洋天然产物的研究进展,malyngamides类化合物是从海藻菌代谢物中分离得到的一类骨架结构新颖的海洋天然产物,由于其特殊的生长环境,表现出良好的生物活性.本文结合自己的研究工作详细叙述了malyngamides类海洋天然产物的最新研究进展.第2章介绍了丝氨醇衍生的malyngamides的立体选择性合成,以正十四醛的不对称烯丙基化反应,在叔丁基锂的作用下手性末端炔和保护的3-溴-1-丙醇的偶联反应为关键步骤完成了（S）-7-甲氧基-4E-二十烯碳酸的合成,以D-丝氨酸为天然手性源完成了氨片段（R）-甲氧基甲基氨基丙醇的合成,通过酰胺键将手性不饱和脂肪酸和氨片段连接完成了一个目标分子的合成,再经过乙酰化反应可以得到另一个目标分子.同时用类似的方法,以L-丝氨酸为天然手性源合成了它们的C-1′位异构体.第3章叙述了用9步反应、12%的总产率完成了malyngamide M的首次全合成.以邻甲苯酚的Friedel-Crafts酰基化和Wittig反应为关键步骤完成了氨片段的合成,同时利用第2章中酸部分的制备方法,以及以Johnson-Claisen重排为关键步骤的合成方法,分别以23%和50%的总产率完成了（S）-7-甲氧基-4E-十四碳烯酸的合成.随后将手性不饱和脂肪酸和氨片段进行酰胺化反应构筑了malyngamide M的基本骨架,再将Z-烯氯转化为E-烯氯完成了目标分子的全合成,高立体选择性地构筑了末端烯氯结构,为制备其它含有类似烯氯结构的malyngamides探索出行之有效的合成路线.第4章详细阐述了使用高度会聚通用的路线完成含有末端烯氯结构的malyngamides O,P,Q,和R,以及Q和R的C-5″差向异构体的全合成.用前述的Johnson-Claisen重排反应制备（S）-7-甲氧基-4E-十四碳烯酸,以Wittig反应为关键步骤构筑末端烯氯,用天然L-丝氨酸为手性源构筑乙酰基吡咯酮部分.先以malyngamides O和P为试点探索通用合成路线,将乙酸甲酯和烯氯部分在LDA存在下进行aldol反应得到氨部分的骨架,再将手性不饱和脂肪酸和氨部分进行酰胺化反应完成了malyngamide P的合成,将P在碱性条件下进行烯醇甲基化反应完成了malyngamide O的全合成.该合成路线拓展应用到malyngamides Q和R的合成时,首先用酰胺键将手性不饱和脂肪酸和烯氯片段连接,再转化成相应的醛,与乙酰基吡咯酮进行TiCl₄催化的aldol反应即得到malyngamides Q和R的骨架结构,再经过酸催化的烯醇甲基化反应完成了Q和R的全合成.同时以D-丝氨酸为天然手性源完成了malyngamides Q和R的C-5″差向异构体的全合成,确证了Q和R的绝对构型为C-5″S.Malyngamides O,P,Q和R的全合成分别经历了12,11,13和14步反应,总产率分别为6.5%,3.5%,2.3%和3.7%.全文完成了7个malyngamides海洋天然产物的全合成,也完成了它们的5个异构体的制备,论文涉及了60个新化合物（包括中间体）的制备.本文解决了海洋天然产物含量低,难以富集分离提取的难题,提供了一定的物质量可深入细致地进行malyngamides类海洋天然产物的生物活性研究.本文中阐述的合成方法也可拓展到其它类似结构malyngamides的合成中,丰富了天然产物全合成和有机合成方法学的内容.更多还原

【Abstract】 This thesis was concerned with the studies on the marine natural product with novel skeleton structure-total synthesis of malyngamides.It mainly consists of the following four parts:First,the recent progress in research of malyngamides had been reviewed. Malyngamides with novel structure,a series of marine L.majuscule,and their good biological activity is owing to their special living environment.In this part,we summarized the recent studies on the progress of malyngamides on the basis of our groups’ work.In chapter 2,the stereoselective synthesis of serinol-derived malyngamides was introduced.The key steps of the synthesis of E,(7S)-7-methoxyeicos-4-enoic acid involved the catalytic asymmetric allylation of octanal and the coupling reaction of a chiral alkyne with a protected bromide in the presence of t-BuLi.Natural chiral pool D-serine was selected as starting material for the construction of the amine portion (R)-methoxyamino alcohol.The amidation reaction of the chiral unsaturatecd acid with the amine accomplished the synthesis of one target molecule.Acetylation of it finished the preparation of another target molecule.Their 1’-epi-isomers have also been synthesized with a similar strategy using L-serine as natural chiral pool.In chapter 3,the first total synthesis of malyngamide M was accomplished in nine steps in 12%yield.The key steps involved Friedel-Crafts reaction of o-cresol and the Wittig reaction for construction the skeleton of amine moiety,at the same time, using the synthesis of E,(7S)-7-methoxytetradec-4-enoic acid in chapter 2,and Johnson-Clainsen rearrangement as a key step for construction the fatty acid part,the corresponding acid was prepared in 23%and 50%overall yield,respectively.The amidation of fatty acid with amine constructed the skeleton of malyngamide M,and then transformation of Z-olefin to E-olefin completed the synthesis of target molecule. The construction of vinyl chloride functionally in highly selectivity should offer a reference value for the synthesis of other structurally related malyngamides containing vinyl chloride structure. At last,a convergent and general protocol to marine natural product,as demonstrated by the enantioselective total synthesis of malyngamides O,P,Q,R, 5"-epi-Q and 5"-epi-R bearing terminal vinylic chloride structure,was developed in detail.E,(7S)-7-methoxytetradec-4-enoic acid was prepared using the above described Johnson-Clainsen rearrangement,the terminal vinyl chloride was constructed using Wittig reaction as key step,the pyrrolidone derivative was constructed using L-serine as natural chiral pool.Starting from the synthesis of malyngamides O and P to explore the general route,an aldol reaction of methyl acetate with the vinyl chloride part in the presence of LDA gave the skeleton of amine portion,followed by amidation with the fatty acid finished the synthesis of malyngamide P.Subsequently,enol methylation of P in basic condition completed the synthesis of malyngamide O.Applied this route to the synthesis of malyngamides Q and R,the chiral unsaturated acid was connected with the vinyl chloride part by amidation,then the resulting product was converted into the corresponding aldehyde,followed by aldol condensation of the aldehyde with the chlorotitanium enolate of pyrrolidone to complete the skeleton of malyngamides Q and R,then the synthesis of them was completed via enol methylation in acid condition.The determination of absolute configurantions of C-5" as S in amine portion of Q and R were accomplished by the total synthesis of their diastereomers. The synthesis of malyngamides O,P,Q,and R were accomplished by a longest linear sequence of 12,11,13,and 14 steps in 6.5%,3.5%,2.3%and 3.7%overall yield, respectively.The seven target molecules of malyngamides and their five isomers were synthesized in this thesis which involved in the preparation of 60 new compounds. Synthesis of marine natural products solved problem about the scarcity of malyngamides in natural sources and the difficuty in enriching and extracting these materials,and provided materials for more extensive biological evaluation.The synthetic methods in the thesis should extend the preparation of other structurally related malyngamides containing the similar vinyl chloride structure and enrich the content of total synthesis of natural products and organic synthetic methodology.更多还原