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Asymmetric Reactions in Water Catalyzed by L-Proline Tethered on Thermoresponsive Ionic Copolymers
Letters in Organic Chemistry ( IF 0.7 ) Pub Date : 2020-08-31 , DOI: 10.2174/1570178616666190819141307
Noriyuki Suzuki 1 , Daisuke Mizuno 1 , Armando M. Guidote 1 , Shun Koyama 1 , Yoshiro Masuyama 1 , Masahiro Rikukawa 1
Affiliation  

L-Proline was covalently tethered on thermoresponsive ionic block copolymers that formed micelles in aqueous solutions. The block copolymers consisted of a poly(N-isopropylacrylamide) (PNIPAAm) segment and an anionic or cationic polymer segment. These copolymers exhibited lower critical solution temperature (LCST) behavior at ca. 35-40°C, and achieved thermal stimuli-induced formation and dissociation of micelles. The copolymer generated micelles in aqueous solution at a higher temperature, where a catalytic aldol reaction proceeded with high diastereo- and enantioselectivities. The micelles dissociated at lower temperature to form a clear solution such that the products could be efficiently extracted from the aqueous reaction mixture. Extraction of the aldol product with an organic solvent from the aqueous solution of the anionic copolymer was more efficient than from the nonionic copolymer solution.



中文翻译:

热响应性离子共聚物上束缚的L-脯氨酸催化的水中不对称反应

L-脯氨酸共价连接在热响应性离子嵌段共聚物上,该共聚物在水溶液中形成胶束。该嵌段共聚物由聚(N-异丙基丙烯酰胺)(PNIPAAm)链段和阴离子或阳离子聚合物链段组成。这些共聚物在约200℃下显示出较低的临界溶液温度(LCST)行为。在35-40°C的温度下,实现了热刺激诱导的胶束形成和分解。该共聚物在较高温度下在水溶液中产生胶束,其中催化醛醇缩合反应以高非对映选择性和对映选择性进行。胶束在较低温度下解离形成透明溶液,从而可以从含水反应混合物中有效地提取产物。

更新日期:2020-08-31
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