Synthesis and structure elucidation of a new [2]-catenane
作者:Christopher A. Hunter
DOI:10.1021/ja00039a047
日期:1992.6
A supramolecular self-assembly process has lead to the synthesis of new type of [2]-catenane. A 34% yield of catenane was obtained from a one-pot double macrocyclization reaction. Its three-dimensional structure was determined structure was determined by using two-dimensional 1 H NMR spectroscopy. This structure agrees well the predictions of molecular mechanics calculations, altough there is some
超分子自组装过程导致了新型[2]-链烯的合成。从一锅双大环化反应中获得了 34% 的链烷烃收率。其三维结构确定 结构通过二维 1 H NMR 光谱确定。这种结构与分子力学计算的预测非常吻合,尽管其中一个酰胺键的取向有些模糊。该分子通过几个大环间 H 键和 π-π 相互作用锁定在明确定义的构象中,正是这些相互作用为联锁环系统的组装提供了模板。通过变温 1 H NMR 研究了链烷烃的动态特性
Directed macrocyclisation reactions
作者:Fiona J. Carver、Christopher A. Hunter、Richard J. Shannon
DOI:10.1039/c39940001277
日期:——
Macrocyclic hosts are prepared in 80–90% yields by using intramolecular hydrogen-bonding interactions to direct the cyclisation; in the absence of such effects, intermolecular hydrogen-bonding interactions template the formation of catenanes.
A series of new rotaxanes with axles different in length was prepared. Following the synthetic protocol utilizing a known anion template effect (Scheme 1), surprisingly low yields in the order of 2 - 5% were obtained (Scheme 3), which furthermore significantly depended on the nature of the stopper (Fig. 1). Variations in the synthetic procedures and computational results from Monte Carlo simulations allowed us to analyze the origin of these findings: The rotaxane wheel 3 acts as a noncovalently bound 'protecting group' for the stopper nucleophile. The protection of the nucleophilic phenolate O-atom depends much on the steric demands of the stoppers (see 2 vs. 10) which induce different conformations of the wheel. Based on this model. an improved synthetic scheme is suggested.
Hunter Christopher A., Purvis Duncan H., Angew. Chem., 104 (1992) N 6, S 779-782