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Cylindrical macrocyclic compounds synthesized by connecting two bowl-shaped calix[3]aramide moieties: structures and chiroptical properties†
Ryoko Sakagami,Yuuki Saito,Ryuichi Mori,Misa Satake,Misaki Okayasu,Shoko Kikkawa,Hidemasa Hikawa,Isao Azumaya
RSC Advances Pub Date : 09/18/2020 00:00:00 , DOI:10.1039/D0RA07060B
Abstract

Calix[3]aramide-based macrocycles 1 were successfully synthesized by a Glaser coupling reaction of two meta-calix[3]aramide moieties that have three ethynyl groups. The obtained macrocycles have stereoisomers: an enantiomeric pair and a meso form based on a combination of amide bond directions in the calix[3]aramide moieties at both ends of the molecule. Characteristic absorption spectra derived from the 1,4-diphenylbutadiyne structure were observed, while their ECD spectra were mirror-images. Single-crystal X-ray analysis revealed that each stereoisomer had a cylindrical rigid shape, and the absolute structure of the chiral-form was also assigned by comparing the Flack parameters. Mirror-image VCD spectra were observed for the enantiomeric chiral forms, and a VCD signal pattern of one enantiomer corresponded to that predicted by the relationship between the dihedral angle of the pair of C[double bond, length as m-dash]O groups.

Graphical abstract: Cylindrical macrocyclic compounds synthesized by connecting two bowl-shaped calix[3]aramide moieties: structures and chiroptical properties
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