Constitutional Isomers of Pentahydroxy-Functionalized Pillar[5]arenes: Synthesis, Characterization, and Crystal Structures

We herein report the preparation
of constitutional isomers of pentahydroxy-functionalized
pillar[5]­arenes via the deprotection of their benzylated derivatives
by catalytic hydrogenation. The structures of the obtained isomers
were then established using single crystal X-ray diffraction. We also
found that the yield distribution of the different constitutional
isomers was dependent on the nature of the substitution, as revealed
by HPLC analysis of the crude mixture. Finally, further characterization
of the separated constitutional isomers indicated that they possess
different melting points, NMR spectra, crystal structures, and stacking
patterns in the solid state.

本文报道了通过催化氢解脱苄基化反应，制备五羟基官能化柱[5]芳烃（pillar[5]arene）构造异构体（constitutional isomers）的方法。随后借助单晶X射线衍射（single crystal X-ray diffraction）确定了所获异构体的分子结构。通过对粗产物混合物的高效液相色谱（High Performance Liquid Chromatography, HPLC）分析可知，不同构造异构体的产率分布与取代基性质密切相关。最后，对分离得到的构造异构体开展进一步表征，结果显示其在固态状态下分别具有不同的熔点、核磁共振波谱（Nuclear Magnetic Resonance, NMR）、晶体结构以及堆积模式。