Synthesis of chiral calix[4]arenes bearing aminonaphthol moieties and their use in the enantiomeric recognition of carboxylic acids

Abstract

Two armed chiral calix[4]arenes 8-16 functionalized at the lower rim with chiral aminonaphthol units have been prepared and the structures of these receptors characterized by FTIR, (1)H, and (13)C, DEPT and COSY NMR spectroscopy and elemental analysis. The enantioselective recognition of these receptors with various carboxylic acids has been studied by (1)H NMR and UV/Vis spectroscopy. The receptors exhibited different chiral recognition abilities towards the enantiomers of racemic materials and formed 2 : 1 or 1 : 1 complexes between host and guest. It was also demonstrated that chiral calix[4]arenes 9 and 16 could be used as chiral NMR solvating agents to determine the enantiomeric purity of mandelic acid.

Chiral calix[4]arenes bearing aminonaphthol moieties as membrane carriers for amino acid methyl esters and mandelic acid

“…For the desired goal, dibromo calix[4]arene 1 was chosen as the starting material, and the synthetic route is shown in Scheme 1. Compounds 4-7 were prepared according to the previously published procedures, 27 while reaction steps leading to 2 and 3 are described for the first time.…”

Biomimetic Molecular Recognition Elements for Chemical Sensing

“…The shape and chiral selective capabilities of calixarene-based coatings have shown to offer a solution to the selectivity problem of several sensing platforms. As another recent example, researchers have demonstrated that chiral calix [4]arenes functionalized with aminonaphthol moieties were capable of selective chiral recognition of mandelic acid, a useful precursor to various drugs [105]. As future biomimetic calixarene systems emerge and are refined, we will continue to witness improvements in our chemical-sensing capability as well as our analytical systems for assessing enantiomeric purity of pharmaceuticals.…”

Amino alcohol based chiral solvating agents: synthesis and applications in the NMR enantiodiscrimination of carboxylic acids

“…Enantiodifferentiation in the spectra simply requires the use of a chiral auxiliary that converts a mixture of enantiomers into a mixture of diastereoisomeric complexes. 17 In a continuation of our work on the synthesis of chiral receptors based on the calix [4]arene platform equipped with various functionalities including azacrown ethers, 18 amines, 19 amides, 20 Schiff bases, 21 and quaternary ammonium salts 22 as well as their catalytic activities and enantiomeric recognition properties towards chiral amines, carboxylic acids, 23 and amino acid derivatives, 24 we herein report the synthesis of novel chiral receptors and their recognition abilities for carboxylic acids by 1 H NMR spectroscopy.…”