Abstract

Polymer-based nanoreactor, which can be achieved by self-assembling of amphiphilic polymers in water, has attracted more and more attention in recent years. In this study, a kind of Pd-nanoreactor was fabricated by self-assembling of chiral palladium complex-containing amphiphilic polymers in water. Firstly, chain transfer reagent (CTA) CEPA-PyOx was obtained by condensation reaction of (S,S)-4-hydroxymethyl-5-phenyl-2-(2′-pyridinyl)-1,2-oxazoline (PyOx) and 4-cyano-4-[((ethylthio)carbonothioyl)thio] pentanoic acid (CEPA) in the presence of EDC·HCl. Next, polymethacrylate with a terminal chiral oxazoline ligand (CEPA-POEGMA₃₆-PyOx) was synthesized through Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization. After removal of the thioester bond and coordination with palladium trifluoroacetate, the polymer self-assembled in water affording Pd-nanoreactor, which possess core-shell structure and with chiral palladium complex in the core. At last, the nanoreactor was successfully applied in the asymmetric catalytic synthesis of flavanone in aqueous phase, and the catalyst loading was greatly reduced compared to unsupported palladium complex. In the presence of low palladium loading (0.5 mol%), flavanone was successfully synthesized with excellent yield (98%) and high enantioselectivity (82%).

Graphic Abstract

中文翻译：

---

基于末端官能化聚甲基丙烯酸酯的纳米反应器的制备及其催化应用

摘要

可以通过两亲性聚合物在水中自组装获得的基于聚合物的纳米反应器近年来受到越来越多的关注。本研究通过在水中自组装含手性钯配合物的两亲性聚合物制备了一种Pd纳米反应器。首先，通过（S，S）-4-羟甲基-5-苯基-2-（2'-吡啶基）-1,2-恶唑啉（PyOx）与4的缩合反应获得链转移剂（CTA）CEPA-PyOx在EDC·HCl存在下的-氰基-4-[[（（乙硫基）羰基硫酰基）硫基]戊酸（CEPA）。接下来，用末端手性恶唑啉配体的聚甲基丙烯酸酯（CEPA-POEGMA ₃₆-PyOx）是通过可逆加成-断裂链转移（RAFT）聚合反应合成的。除去硫酯键并与三氟乙酸钯配位后，该聚合物在水中自组装，得到Pd-纳米反应器，该反应器具有核-壳结构并且在核中具有手性钯配合物。最后，该纳米反应器成功应用于水相中黄烷酮的不对称催化合成中，与未负载的钯配合物相比，催化剂的负载量大大降低。在低钯载量（0.5摩尔％）的存在下，成功合成了黄烷酮，具有极好的收率（98％）和高对映选择性（82％）。

图形摘要