hexagonal columnar phase mediated by macrocyclic host–guest (H–G) interactions between the macrocycles and alkylammonium salts. The phase transition, triggered by an organic guest engaging in H–G interactions with a macrocyclic cavity, provides a novel strategy for manipulating the properties of liquid‐crystalline materials. The crystal structure of a homologous cyclo[6]aramide reveals a disk‐shaped, near‐planar
Highly Efficient, One-Step Macrocyclizations Assisted by the Folding and Preorganization of Precursor Oligomers
作者:Lihua Yuan、Wen Feng、Kazuhiro Yamato、Adam R. Sanford、Dingguo Xu、Hua Guo、Bing Gong
DOI:10.1021/ja0474547
日期:2004.9.1
Highly efficient, one-step macrocyclizations leading to the formation of macrocyclic hexa(aramides) in high yields (69-82%) are described. The one-step macrocyclizations were facilitated by the preorganization or folding of the backbones of uncyclized precursors in the course of macrocyclization. The preorganization of backbones was achieved by the presence of localized three-centered hydrogen bonds
Oligoamide macrocycles consisting of eight meta-linked benzene residues were synthesized based on the cyclization of aromatic oligoamide precursors having folded backbones rigidified by three-center hydrogen bonds. An alternative route based on the condensation of pentadimeric diamine and trimeric diacid provided the cyclic octamer in 75% yield using EDCI/HOBt as the coupling reagent.