手性樟脑三齿席夫碱配体的合成及催化性能研究

【作者】 刘伟春；

【导师】 徐峰；

【作者基本信息】 陕西师范大学 ， 有机化学， 2011， 硕士

【摘要】 由于手性化合物在医药、化学和生物学等领域的特殊作用,获得手性化合物的不对称合成方法就成为人们研究的热点。而在不对称合成的方法中,通过手性催化剂诱导的催化不对称合成只需要催化量的手性化合物就可以获得大量的光学活性物质。所以这种不对称合成方法效率高、生产成本低,这也正是其魅力所在。不对称合成的核心问题是手性中心的产生和控制。手性配体作为手性诱导试剂对产物的光学纯度起着关键的作用,因此,人们对手性配体的研究较为深入。由手性氨基醇合成的手性三齿席夫碱配体具有原料价格便宜,合成方法简单,实用范围广等多种优点,备受化学家的青睐。在手性三齿席夫碱配体的设计中,手性氨基醇的选择和对水杨醛的修饰非常重要,对配体的手性识别的效果影响很大。天然手性化合物樟脑,只含一种对映体,用它做起始原料,可以利用其已有的手性中心,在分子的适当部位引入新的官能团,得到多种有用的手性配体,且樟脑类化合物由于其独特的立体结构和电子效应,已经在不对称合成反应中得到了广泛的应用,表现出较好的立体诱导效应。基于上述研究背景,本论文合成了两种天然手性樟脑衍生的氨基醇。一种是从樟脑出发合成樟脑醌-3-肟,用氢化铝锂试剂将其选择性还原得到2-羟基-3-氨基樟脑氨基醇；另一种是以樟脑磺酸为原料,经过四步反应使其转化为1-氨基-2-羟基樟脑氨基醇。并以这两种手性氨基醇为基础与水杨醛及其衍生物进行缩合,合成了15种手性樟脑三齿席夫碱配体,通过红外、核磁共振氢谱、核磁共振碳谱对合成的席夫碱配体进行了结构表征和确认。基于此类配体具有独特的立体结构和电子效应,我们将此类配体与乙酸铜络合,用于催化硝基甲烷与对硝基苯甲醛的不对称Henry反应。研究了配合物结构对催化性能和立体选择性的影响,并以此为基础,对催化剂的用量、反应温度、溶剂等反应条件进行了筛选。在最优反应条件下,将其用于催化其它醛与硝基甲烷的不对称Henry反应。论文主要包括三个部分：第一章对手性三齿席夫碱配体和过渡金属形成的络合物在不对称反应中的研究进展做了综述；第二章包括樟脑氨基醇,水杨醛衍生物及席夫碱配体的合成与表征；第三章研究了合成的手性樟脑三齿席夫碱配体与乙酸铜络合催化不对称Henry反应。更多还原

【Abstract】 The special function of chiral compounds has been gradually realized in medical treatment, chemical, and biological and other related fields. Asymmetric synthesis method for the chiral compounds is becoming hot topic. Among these methods of asymmetric synthesis, the chiral catalyst induced asymmetric synthesis, which only needs catalytic amount of chiral compound, can produce a large amount of optically active substances. Therefore, the asymmetric catalytic synthesis method is a high efficiency procedure to prepare chiral compounds, while reducing production costs. It is also a charming point of asymmetric catalytic synthesis.The core problem of asymmetric synthesis are the chiral center’s generation and control in asymmetric catalytic synthesis, the chiral centres of ligands play a key role as chiral inducing agents on the formation of optical purity products. Therefore, the synthesis of chiral ligand and study of its intermediator in the catalytic cycles become a more abstruse area. Chemists have discovered and synthesized thousands of chiral ligands and complexes with different structures, among them, tridentate Schiff base which is synthesized by chiral amino alcohol has numerous advantages and highly favored. For example, synthesis method is simple, raw materials are cheap, and they have widely practical application. In designing of chiral tridentate Schiff base ligand, the choice of chiral amino alcohols and salicylaldehyde modification is very important which often directly affect the chiral ligand recognition effect. Natural chiral compounds camphor only contain a enantiomers, using it as starting materials, we can utilize their existed chiral centers, and introduce new functional groups to the appropriate parts of the molecule to make many useful chiral ligands. Furthermore, compound derived from camphor has been widely applied in asymmetric synthesis due to their unique stereo structure and electronic effects. They have showed a good stereo induction effects in asymmetric catalysis.Based on the above research background, we synthesized two kind of chiral amino alcohol derived from natural chiral camphor. One is 3-amino-1,7,7-trimethylbicyclo[2.2.1] heptan-2-ol, which is synthesized by selectively reduction camphor quinone 3-oxime with LiAlH4. The other is 1-amino-7,7-dimethylbicyclo[2.2.1]heptan-2-ol, which is obtained by four-step reaction using camphor sulfonic acid as raw material. The two amino alcohol was used as starting material, condensed with salicylaldehyde and its derivatives, totally 15 chiral tridentate Schiff base ligand derived from natural camphor are synthesized. All compounds were characterized by IR,1H-NMR and 13C-NMR, the analysis dates of these compounds are identical with the anticipated. Based on such ligand with the unique structures and electronic effects, we have made them complex with acetic acid copper. Asymmetric Henry reaction of nitromethane and p-nitrobenzaldehyde is catalyzed by those Schiff-base complexes. We screened these complexes and discussed the relationship of catalytic performance and stereoselectivity of ligands. On this basis, the amount of catalyst, reaction temperature, solvent and other reaction conditions were optimized. Under the optimal reaction conditions, other aldehydes and nitromethane’s asymmetric Henry were catalyzed by above catalyst.This thesis consists of three parts, the first chapter review the research progress of chiral ligand complexes made from tridentate Schiff base ligand and transition metal in asymmetric reactions; The second chapter report the synthesis and characterization of two chiral amino alcohol derived from camphor, derivatives of salicylaldehyde and the schiff base ligands; In the third chapter, asymmetric Henry reaction is catalyzed by complexs which synthesized by base ligand and copper acetate.更多还原