节点文献
氮杂环卡宾和有机膦小分子催化的Domino反应研究
【作者】 马俭泽；
【导师】 陈茹玉；
【作者基本信息】 南开大学 ， 有机化学， 2011， 硕士
【摘要】 有机催化的Domino反应往往在很大程度上接近“理想合成”的标准。因此,其在天然产物全合成和药物分子的工业化上有重要的用途。氮杂环卡宾是一种独特的有机催化剂。它主要遵循“极性转换”的催化模式,能催化其他有机催化剂难以实现的Domino反应。因此,可以为复杂化合物的合成设计提供新的思路。在第一章我们对NHC催化的Domino反应进展作了综述。经研究,我们发现了一种氮杂环卡宾催化的三组分Domino反应。通过NHC催化的查尔酮,肉桂醛和炔丙醇的三组分Domino反应高效合成了一系列多取代的顺式ε-酮酯。本反应经历了一个crossed-benzoin/oxy-Cope rearrangement/ esterification Domino过程,同时构筑了两个新的化学键。通过引入炔丙醇,大幅度地提高了该类化合物的合成效率。本反应底物应用范围广(23 examples),收率高(51-98%),非对映选择性好(up to 20:1),从而丰富了1,6-二羰基化合物这类重要合成砌块的合成策略。有机膦小分子也是一种受到广泛关注的亲核性有机催化剂,它能有效地把反应底物转化为活泼中间体,因而广泛应用在多种环化反应中。第三章主要介绍了我们首次发现的底物控制,三丁基膦催化的基于活化共轭双烯Rauhut-Currier (RC)反应的Domino反应。通过引入活化共轭双烯,有效避免了“交叉反应选择性差”,“产物容易聚合”这两个传统简单烯烃参与的RC反应所固有的缺点。首次提出了三丁基膦催化分子间RC反应形成膦叶立德中间体的反应机理。利用此Domino反应,可以高非对映选择性地构筑具有四个连续手性中心的双环二氢呋喃结构,同时生成三个新的化学键。通过修饰共轭双烯的结构首次高效合成了具有两个手性中心的双环戊烯膦烷类化合物,同时构筑了四个新的化学键。
【Abstract】 The introduction of domino reaction as a concept into organic synthesis has inspired fruitful discoveries. They have great potential to meet several new criteria of an’ideal synthesis’, namely atom, step, and redox economy.N-heterocyclic carbenes, as special and robust organocatalysts, have made an impressive contribution to the unprecedented domino reactions; and therefor opened a new pathway to the rapid formation of molecular complexity.Herein, a novel NHC-catalyzed three-component domino strategy to access highly functionalized acyclic cis-ε-ketoesters with excellent yields and high stereoselectivities is documented. This domino reaction is atom economical and works on a broad range of substrates. The relative stereochemistry could be explained by a cascade crossed-benzoin/oxy-Cope rearrangent/esterification process. The obtained product was further functinalized to a useful building block for organic synthesis.Phosphine organocatalysts have been subjected to intensive studies and have manifested their undeniable power in cyclization processes.We have developed unprecedented substrate-controlled and tripbutylphosphine-mediated domino reactions with high diastereoselectivities. A mechanism featuring the involvement of a ylide generated by intermolecular Rauhut-Currier (RC) reaction of activated conjugated diene was for the first time described. These domino reactions can provide bicyclic dihydrofuran derivatives with four contiguous stereogenic centers and bicyclic phosphoranes via a catalytic model and a catalytic-stoichiometric model, respectively.