pH-Responsive copolymers with reversible transformation ability have been investigated as new effective carriers for L-proline to catalyze asymmetric aldol reaction in water. A series of block copolymers of mPEG-b-P(DEA_x-co-L-ProlA_y) (mPEG-PDL) bearing L-proline catalytic sites and pH-responsive poly (diethylaminoethyl methacrylate) (PDEA) segments were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of methyl polyethylene glycol (mPEG) trithiocarbonate macro-RAFT agent. The pH-induced self-assembly behaviors of three copolymer catalysts with different contents of PDEA were investigated via the combination of UV–visible spectrometer (UV–vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). Catalytic activity and stereoselectivity of these copolymer catalysts were evaluated by direct asymmetric aldol reaction of p-nitrobenzaldehyde and cyclohexanone in water. The results indicated that catalytic activity and stereoselectivity effected by the pH value of aqueous solution and the structures of copolymer catalyst assemblies. mPEG-PDL-2 give the aldol product with high conv., yield, anti/syn, and ee (92%, 91%, 92/8, 96%), respectively at pH 7.0. Furthermore, these pH-responsive copolymers supported L-proline are easily recycled by a reversible phase transition.

已经研究了具有可逆转化能力的pH响应共聚物作为L-脯氨酸催化水中不对称羟醛反应的新型有效载体。mPEG- b -P（DEA _x - co -L-ProlA _y的一系列嵌段共聚物）通过在甲基聚乙二醇（mPEG）三硫代碳酸酯存在下可逆的加成-断裂链转移（RAFT）聚合反应合成带有L-脯氨酸催化位点和pH响应的聚甲基丙烯酸二乙氨基乙酯（PDEA）片段的（mPEG-PDL）宏RAFT代理。通过紫外可见光谱仪（UV-vis），动态光散射（DLS）和透射电子显微镜（TEM）的组合，研究了三种具有不同PDEA含量的共聚物催化剂的pH诱导自组装行为。催化活性和这些共聚物的催化剂的立体选择性是由直接不对称醛醇缩合反应进行评价p-硝基苯甲醛和环己酮在水中。结果表明，催化活性和立体选择性受水溶液的pH值和共聚物催化剂组装体结构的影响。的mPEG-PDL-2，得到具有高CONV醛醇缩合产物，产率，防/顺式，和EE（92％，91％，92/8 ， 96％），分别在pH 7.0。此外，这些pH响应性共聚物负载的L-脯氨酸易于通过可逆相变再循环。