Institute for Molecular Design and Synthesis, School of Pharmaceutical Science & Technology, Health Science Platform, Tianjin University , 92 Weijin Road, Nankai District, Tianjin 300072, People's Republic of China.
Laboratory of Organic Chemistry, Wageningen University , Stippeneng 4, 6703 WE Wageningen, The Netherlands.
J Am Chem Soc. 2018 Jan 10;140(1):74-77. doi: 10.1021/jacs.7b10767. Epub 2017 Dec 29.
The synthesis of "rim-differentiated" C-symmetric pillar[5]arenes, whose two rims are decorated with different chemical functionalities, has remained a challenging task. This is due to the inherent statistical nature of the cyclization of 1,4-disubstituted alkoxybenzenes with different substituents, which leads to four constitutional isomers with only 1/16th being rim-differentiated. Herein, we report a "preoriented" synthetic protocol based on FeCl-catalyzed cyclization of asymmetrically substituted 2,5-dialkoxybenzyl alcohols. This yields an unprecedented 55% selectivity of the C-symmetric tiara-like pillar[5]arene isomer among four constitutional isomers. Based on this new method, a series of functionalizable tiara-pillar[5]arene derivatives with C-symmetry was successfully synthesized, isolated, and fully characterized in the solid state.
“边缘区分”的 C 对称柱[5]芳烃的合成，其两个边缘用不同的化学官能团装饰，一直是一项具有挑战性的任务。这是由于具有不同取代基的 1,4-二取代烷氧基苯环化的固有统计性质，导致只有 1/16 是边缘区分的四个结构异构体。在这里，我们报告了一种基于 FeCl 催化的不对称取代的 2,5-二烷氧基苄醇环化的“预定向”合成方案。这在四个结构异构体中产生了前所未有的 C 对称冠状柱[5]芳烃异构体 55%的选择性。基于这种新方法，成功地合成、分离和在固态下充分表征了一系列具有 C 对称性的官能化冠状柱[5]芳烃衍生物。
