Abstract Nucleophilic ring-opening reaction of azlactone moieties was used for the immobilization of organocatalysts on smart block copolymers. Copolymerization of N-isopropylacrylamide with 2-vinyl-4,4-dimethylazlactone using a PEG-based macro-RAFT agent afforded temperature-sensitive block copolymers bearing azlactone side groups. Three different organocatalysts possessing primary amino groups were synthesized on the basis of L-proline and L-prolineamide using standard peptide coupling procedures. Organocatalyst immobilization was achieved using a post-polymerization reaction of the primary amino group with the azlactone moiety. The organocatalyst-functionalized block copolymers exhibited a temperature induced self-aggregation upon exceeding a critical phase transition temperature. The block copolymer aggregates with the immobilized organocatalyst in the core were subjected to the aldol reaction of cyclohexanone and p-nitrobenzaldehyde in water. Good diastereo- and enantioselectivities were observed, particularly for the immobilized prolineamides. Organocatalyst separation and reusability was demonstrated for five reaction cycles with no loss in catalyst reactivity. Finally, the applicability of the immobilized organocatalyst to the aldol reaction of cyclohexanone with differently substituted benzaldehydes in water was shown.

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用于有机催化剂固定的吖内酯功能化智能嵌段共聚物

摘要 吖内酯部分的亲核开环反应用于将有机催化剂固定在智能嵌段共聚物上。N-异丙基丙烯酰胺与 2-乙烯基-4,4-二甲基吖内酯使用基于 PEG 的大分子 RAFT 试剂共聚，得到带有吖内酯侧基的温度敏感嵌段共聚物。使用标准肽偶联程序在 L-脯氨酸和 L-脯氨酸酰胺的基础上合成了三种不同的具有伯氨基的有机催化剂。使用伯氨基与吖内酯部分的后聚合反应实现了有机催化剂的固定。有机催化剂官能化的嵌段共聚物在超过临界相变温度时表现出温度诱导的自聚集。在核心中具有固定化有机催化剂的嵌段共聚物聚集体在水中进行环己酮和对硝基苯甲醛的羟醛反应。观察到良好的非对映选择性和对映选择性，特别是对于固定化脯氨酸酰胺。有机催化剂的分离和可重复使用性在五个反应循环中得到证明，催化剂反应性没有损失。最后，显示了固定化有机催化剂对环己酮与不同取代的苯甲醛在水中的羟醛反应的适用性。有机催化剂的分离和可重复使用性在五个反应循环中得到证明，催化剂反应性没有损失。最后，显示了固定化有机催化剂对环己酮与不同取代的苯甲醛在水中的羟醛反应的适用性。有机催化剂的分离和可重复使用性在五个反应循环中得到证明，催化剂反应性没有损失。最后，显示了固定化有机催化剂对环己酮与不同取代的苯甲醛在水中的羟醛反应的适用性。