Kinetic studies of a vinylcyclopropane (VCP) cycloaddition, catalyzed by peptide-based thiyl radicals, are described. Reactions were analyzed by using reaction progress kinetic analysis, revealing that ring-opening of the VCP is both rate- and enantio-determining. These conclusions are further corroborated by studies involving racemic and enantiopure VCP starting material. Noncovalent interactions play key roles throughout: both the peptide catalyst and VCP exhibit unproductive self-aggregation, which appears to be disrupted by binding between the catalyst and VCP. This in turn explains the requirement for the key catalyst feature, a substituent at the 4-position of the proline residue, which is required for both turnover/rate and selectivity.

中文翻译：

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半胱氨酸衍生的硫基催化的不对称乙烯基环丙烷环加成反应的动力学分析反映了许多有吸引力的非共价相互作用

描述了由基于肽的硫自由基催化的乙烯基环丙烷 (VCP) 环加成的动力学研究。通过使用反应进程动力学分析来分析反应，揭示了 VCP 的开环是速率和对映体决定的。涉及外消旋和对映纯 VCP 起始材料的研究进一步证实了这些结论。非共价相互作用在整个过程中发挥着关键作用：肽催化剂和 VCP 都表现出非生产性的自聚集，这似乎被催化剂和 VCP 之间的结合所破坏。这反过来解释了对关键催化剂特征的要求，即脯氨酸残基 4 位上的取代基，这是周转率/速率和选择性所必需的。