Norvaiša Karolis, Yeow Kathryn, Twamley Brendan, Roucan Marie, Senge Mathias O
Chair of Organic Chemistry School of Chemistry Trinity Biomedical Sciences Institute Trinity College Dublin The University of Dublin 152-160 Pearse Street Dublin 2 Ireland.
School of Chemistry Trinity College Dublin The University of Dublin Dublin 2 Ireland.
European J Org Chem. 2021 Mar 26;2021(12):1871-1882. doi: 10.1002/ejoc.202100154. Epub 2021 Mar 22.
Traditional 'picket fence' porphyrin systems have been a topic of interest for their capacity to direct steric shielding effects selectively to one side of the macrocycle. Sterically overcrowded porphyrin systems that adopt macrocycle deformations have recently drawn attention for their applications in organocatalysis and sensing. Here we explore the combined benefits of nonplanar porphyrins and the old molecular design to bring new concepts to the playing field. The challenging -positions of meso-phenyl residues in dodecasubstituted porphyrin systems led us to transition to less hindered and -sites and develop selective demethylation based on the steric interplay. Isolation of the symmetrical target compound [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(3,5-dipivaloyloxyphenyl)porphyrin] was investigated under two synthetic pathways. The obtained insight was used to isolate unsymmetrical [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-nitro-5-pivaloyloxyphenyl)porphyrin]. Upon separation of the atropisomers, a detailed single-crystal X-ray crystallographic analysis highlighted intrinsic intermolecular interactions. The nonplanarity of these systems in combination with 'picket fence' motifs provides an important feature in the design of supramolecular ensembles.
传统的“栅栏式”卟啉体系因其能够将空间屏蔽效应选择性地导向大环的一侧而备受关注。采用大环变形的空间位阻过度拥挤的卟啉体系最近因其在有机催化和传感方面的应用而受到关注。在这里，我们探索非平面卟啉和旧分子设计的综合优势，为该领域带来新的概念。十二取代卟啉体系中中位苯基残基具有挑战性的位置，促使我们转向位阻较小的β和meso位，并基于空间相互作用开发选择性脱甲基反应。在两条合成路线下研究了对称目标化合物[2,3,7,8,12,13,17,18-八乙基-5,10,15,20-四(3,5-二新戊酰氧基苯基)卟啉]的分离。所获得的见解被用于分离不对称的[2,3,7,8,12,13,17,18-八乙基-5,10,15,20-四(2-硝基-5-新戊酰氧基苯基)卟啉]。在分离阻转异构体后，详细的单晶X射线晶体学分析突出了内在的分子间相互作用。这些体系的非平面性与“栅栏式”基序相结合，为超分子组装体的设计提供了一个重要特征。
