Synthesis and Applications
Synthesis and Applications
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DOI：
10.1002/9781119010753.ch2
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
T. B. Reeve;M. Leicester
中科院分区：
文献类型：
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作者：
T. B. Reeve;M. Leicester
本文描述了二醇功能化聚苯乙烯树脂（PS-DVB）的制备，并对其在碳-碳成键反应中作为Lewis酸催化剂的异质化应用进行了初步研究。第1章介绍了背后的动机和方法的使用不溶性聚合物的异质化良好定义的均相催化剂。在第二章中讨论了各种适合接枝到PS-DVB树脂上的隔层改性羟基功能化二醇的途径。接枝步骤是有问题的，醇底物与载体结合的难易程度与它们的空间体积有关。得到了一系列聚合物形态一致的二醇功能化树脂136-140。在第3章中，该方法扩展到通过不对称二羟基化（AD）（168、173和191）或酒石酸（217）从烯烃中得到的尺度二醇。树脂207和208与168和173具有相同的固定二醇单元，也由聚合物结合烯烃的固相AD制备，尽管转化率较低，对映选择性较差。第四章研究了从136-140衍生的钛种作为路易斯酸的使用，并探讨了烷基间隔长度对其在丙烯酸甲酯和环戊二烯的Diels-Alder反应中的活性的影响。九碳亚甲基间隔物（138）的掺入导致催化剂活性相对于源自136和137的催化剂有所改善。尽管存在间隔剂（在139和140中），但与由136-137产生的反应相比，由139和140衍生的催化剂的反应活性明显下降。以（168、173、191和217）为原料制备的钛基路易斯酸在甲基丙烯与环戊二烯和二乙基锌加成苯甲醛的不对称Diels-Alder反应中的应用也有报道，其对映选择性高达39%。136 n = 1 13 7 n = 4 13 8 n = 9 1 39 n = 1 1 40 n = 4
Title: Diol-Functionalised Polystyrene Resins: Synthesis and Applications Author: Toby Benjamin Reeve This thesis describes the preparation of diol-functionalised polystyrenedivinylbenzene (PS-DVB) resins and preliminary investigations into their application for the heterogenisation of Lewis acid catalysts in carbon-carbon bond-forming reactions. Chapter 1 introduces the motivation behind and the methods for the use of insoluble polymers for the heterogenisation of well-defined homogenous catalysts. In chapter 2 a variety of routes to spacer-modified hydroxy-functionalised diols suitable for grafting onto PS-DVB resins are discussed. The grafting step was problematic, the ease with which the alcohol substrates were bound to the support being shown to be related to their steric bulk. A range of diol-functionalised resins 136-140 of consistent polymer morphology was obtained. In chapter 3 this methodology is extended to scalemic diols derived either from olefins by asymmetric dihydroxylation (AD) (168, 173 and 191) or from tartaric acid (217). Resins 207 and 208, with the same immobilised diol unit as for 168 and 173, respectively, were also prepared by solid-phase AD of polymer-bound olefins, although with lower conversion and poorer enantioselectivity. Chapter 4 investigates the use of titanium species derived from 136-140 as Lewis acids and probes the effect of alkyl spacer length on their activity in the Diels-Alder reaction of methyl acrylate and cyclopentadiene. The incorporation of a nine-carbon methylene spacer (138) led to an improvement in catalyst activity relative to catalysts derived from 136 and 137. A significant drop in reactivity was seen in reactions employing catalysts derived from 139 and 140, when compared to those generated from 136-137 despite the presence of the spacer (in 139 and 140). The application of titanium-based Lewis acids prepared from (168, 173, 191 and 217) in the asymmetric Diels-Alder reaction of methacrolein and cyclopentadiene and diethylzinc addition to benzaldehyde is also reported with enantioselectivities of up to 39 % obtained. 136 n = 1 1 3 7 n = 4 1 3 8 n = 9 1 39 n = 1 1 40 n = 4