Supramolecular Catalysis of a Unimolecular Transformation: Aza-Cope Rearrangement within a Self-Assembled Host
作者:Dorothea Fiedler、Robert G. Bergman、Kenneth N. Raymond
DOI:10.1002/anie.200461776
日期:2004.12.10
Bohlmann,F. et al., Chemische Berichte, 1968, vol. 101, p. 2510 - 2518
作者:Bohlmann,F. et al.
DOI:——
日期:——
Supramolecular Catalysis of Unimolecular Rearrangements: Substrate Scope and Mechanistic Insights
作者:Dorothea Fiedler、Herman van Halbeek、Robert G. Bergman、Kenneth N. Raymond
DOI:10.1021/ja062329b
日期:2006.8.1
hypothesis is also supported by quantitative NOE studies of two encapsulated substrates, which place the two reacting carbon atoms in close proximity. The capsule can act as a true catalyst, since release and hydrolysis facilitate catalytic turnover. The question of product hydrolysis was addressed through detailed kinetic studies. We conclude that the iminium product must dissociate from the cavity interior
包含空腔的金属配体组件被用作烯丙基烯铵阳离子的 3-氮杂 Cope 重排的催化宿主。结合后,所有研究的底物的重排速度都会加快,高达 850 倍。为了了解加速的起源,测量了三种烯铵阳离子的活化参数。这些参数表明超分子结构能够降低重排的熵和焓障碍,并且对底物的微小结构变化高度敏感。空间限制性空腔优先结合紧密堆积的、预先组织的底物构象,类似于过渡态的构象。这一假设也得到了两种封装底物的定量 NOE 研究的支持,使两个反应的碳原子靠得很近。胶囊可以充当真正的催化剂,因为释放和水解促进催化转化。通过详细的动力学研究解决了产物水解的问题。我们得出结论,亚胺盐产物必须在氢氧化物介导的水解之前从腔内部和组件外部解离,并提出聚阴离子主体与现有产物的紧密离子对的中介。