The role of alcohol in the Yb(OTf)3- and Y(OTf)3-catalyzed stereoselective radical polymerization of acrylamides is clarified. The coordination of an alcohol to the metal triflate generates a new complex, which increases both the polymerization rate and stereocontrol compared to those achieved by the metal triflate without an alcohol in the polymerization of N,N-diethylacrylamide. While the lanthanide triflate-catalyzed stereoselective polymerization of acrylamides in MeOH has already been well established synthetically, this is the first example that proves the formation of an alcohol-coordinated catalyst as the active catalyst. Job’s plot suggests that the stoichiometry between Yb(OTf)3 and MeOH in the complex is 1:2. The polymerization rate decreases slightly when MeOD is used instead of MeOH, with a secondary isotope effect of 1.14, strongly suggesting the importance of hydroxyl groups for increasing the reactivity. In contrast, no apparent secondary isotope effect is observed to affect the stereoselectivity. The chirality of the alcohol ligand does not affect the stereoselectivity, illustrating that the stereochemistry is most likely controlled by the penultimate effect, which has already been proposed. Furthermore, the conditions are highly compatible with those for organotellurium-mediated radical polymerization, and the dual control of molecular weight and tacticity is successfully achieved. The role of alcohol in the Yb(OTf)3- and Y(OTf)3-catalyzed stereoselective radical polymerization of acrylamides is clarified. The coordination of two equivalents of alcohol to the metal triflate generates a complex, which increases both the polymerization rate and stereocontrol compared to those without an alcohol. The importance of hydroxyl groups of the alcohol is suggested by the observed secondary isotope effect for the rate enhancement. The conditions are highly compatible with those for organotellurium-mediated radical polymerization, and the dual control of molecular weight and tacticity is successfully achieved.

中文翻译：

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配体加速催化的丙烯酰胺立体控制自由基聚合

阐明了醇在 Yb(OTf)3-和 Y(OTf)3-催化的丙烯酰胺立体选择性自由基聚合中的作用。醇与金属三氟甲磺酸盐的配位产生了一种新的络合物，与在 N,N-二乙基丙烯酰胺聚合中没有醇的金属三氟甲磺酸盐相比，它提高了聚合速率和立体控制。虽然在 MeOH 中镧系元素催化的丙烯酰胺立体选择性聚合已经很好地建立起来，但这是第一个证明形成醇配位催化剂作为活性催化剂的例子。Job 的绘图表明复合物中 Yb(OTf)3 和 MeOH 之间的化学计量比为 1:2。当使用 MeOD 代替 MeOH 时，聚合速率略有下降，次级同位素效应为 1.14，强烈表明羟基对于提高反应性的重要性。相比之下，没有观察到明显的次级同位素效应影响立体选择性。醇配体的手性不影响立体选择性，说明立体化学很可能受倒数第二个效应控制，这已经被提出。此外，该条件与有机碲介导的自由基聚合的条件高度兼容，并成功实现了分子量和立构规整的双重控制。阐明了醇在 Yb(OTf)3-和 Y(OTf)3-催化的丙烯酰胺立体选择性自由基聚合中的作用。两当量的醇与金属三氟甲磺酸盐的配位产生络合物，与没有醇的那些相比，这增加了聚合速率和立体控制。观察到的二级同位素效应表明了醇的羟基的重要性。该条件与有机碲介导的自由基聚合条件高度兼容，成功实现了分子量和立构规整的双重控制。