Cyclic ketene acetals (CKAs) are among the most well-studied monomers for radical ring-opening polymerization (rROP). However, ring-retaining side reactions and low reactivities in homopolymerization and copolymerization remain significant challenges for the existing CKAs. Here, we report that a class of monosaccharide CKAs can be facilely prepared from a short and scalable synthetic route and can undergo quantitative, regiospecific, and stereoselective rROP. NMR analyses and degradation experiments revealed a reaction mechanism involving a propagating radical at the C2 position of pyranose with different monosaccharides exhibiting distinct stereoselectivity in the radical addition of the monomer. Furthermore, the addition of maleimide was found to improve the incorporation efficiency of monosaccharide CKA in the copolymerization with vinyl monomers and produced unique degradable terpolymers with carbohydrate motifs in the polymer backbone.

中文翻译：

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单糖环状乙烯酮缩醛的定量、区域特异性和立体选择性自由基开环聚合

环状乙烯酮缩醛 (CKAs) 是研究最深入的自由基开环聚合 (rROP) 单体之一。然而，保环副反应以及均聚和共聚中的低反应活性仍然是现有 CKA 面临的重大挑战。在这里，我们报道了一类单糖 CKA 可以通过短且可扩展的合成路线轻松制备，并且可以进行定量、区域特异性和立体选择性的 rROP。NMR 分析和降解实验揭示了一种反应机制，涉及吡喃糖 C2 位上的增长自由基与不同单糖的反应，在单体的自由基加成中表现出不同的立体选择性。此外，发现马来酰亚胺的添加可以提高单糖CKA在与乙烯基单体共聚中的掺入效率，并产生在聚合物主链中具有碳水化合物基序的独特的可降解三元共聚物。