A second generation of a substrate-selective dynamic supramolecular catalytic system consisting of a catalyst part and a receptor part, connected by a hydrogen-bonding motif, has been realized based on rational design. The results from analyses of the equilibrium mixture of the species generated by the components of the first generation system led us to selectively lock the cisoid conformation of the catalyst part to increase the amount of the substrate-selective catalytic cavity in the equilibrium mixture. This was realized by strapping the catalyst part by organic synthesis. This strapping led to an increase in substrate selectivity in the pair-wise competitive epoxidations of pyridyl- vs. phenyl-appended styrenes and pyridyl- vs. phenyl-appended stilbenes of both Z- and E- configuration compared to the first generation system, reaching 3.4 : 1 as the highest substrate selectivity for Z-mono-pyridyl-stilbene (27a) vs. the corresponding all-carbon analogue (28a) and for E-dipyridyl-stilbene (26b) vs. the corresponding all-carbon analogue (28b), respectively.
基于合理设计的理念,我们实现了一种第二代底物选择性动态超分子催化系统,该系统由催化部分和受体部分组成,通过氢键连接。通过对第一代系统生成物种的平衡混合物进行分析,我们得出了将催化部分的顺式构象选择性锁定以增加平衡混合物中底物选择性催化腔数量的结论。通过有机合成的方法对催化部分进行约束,实现了这一目标。与第一代系统相比,这种约束导致了在
吡啶基与苯基修饰的
苯乙烯以及
吡啶基与苯基修饰的Z型和E型
二苯乙烯的配对竞争环氧化反应中,底物选择性的提高,最高达到了3.4:1的选择性,分别对应于Z型单
吡啶基
二苯乙烯(27a)与相应的全碳类似物(28a)以及E型二
吡啶基
二苯乙烯(26b)与相应的全碳类似物(28b)。