Chiral phenylazomethine cage

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

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 Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O groups.

Chiral macrocyclic compounds whose absolute configurations were derived from the amide bond direction were synthesized by homo coupling of meta-calix[3]aramide derivatives.

Synthesis and chiroptical properties of cylindrical macrocycles comprising two calix[3]aramide moieties

Calix[3]aramide-based cylindrical macrocycles were synthesized by the one-step amide coupling reaction of a monomer containing two meta-alkylaminobenzoic acid units linked by para-phenylene bridges. The major products included a meso-form and an enantiomeric pair, with stereochemistry derived from the direction of the amide bonds and their fixed conformation. Mirror-image ECD, VCD, and CPL spectra were observed in the enantiomeric pair and the absolute structure was determined by comparing measured and calculated ECD and VCD spectra.

Diastereoselective cyclization of an aminobenzoic acid derivative and chiroptical properties of triple-stranded helical bis(phenylethynyl)benzene

Diastereoselective cyclic trimerization of 2,5-dibromo-4-hexylaminobenzoic acid followed by a Sonogashira–Hagihara coupling reaction constructed the triple-stranded helical structure of bis(phenylethynyl)benzene units.

Enantiopure supramolecular cages: synthesis and chiral recognition properties

Enantiopure compounds are ubiquitous in the chemical sciences and present a particular interest in the field of molecular recognition and host-guest systems. Indeed, chiral molecular receptors are at the basis of numerous biological recognition processes and have important implications in biochemistry or pharmacology. Chemists have been investigating this field for several decades, which has led to the development of the synthesis of chiral hosts, their enantiomeric differentiation, and the studies of their recognition properties towards important and bio-relevant chiral guest substrates. The design of molecular cages is a rather difficult task that is even more demanding when enantiopure molecules are required. In this review we chose to present the main families of synthetic organic supramolecular cages that have been developed, whose structures contain stereogenic centers or present an inherent chirality, giving rise to chiral supramolecular cages. Particular attention is given to obtaining enantiopure compounds. Their recognition properties are also underlined. A last important aspect of the review is to present how chiroptical spectroscopies can be used to characterize the recognition phenomena displayed by supramolecular cages.