Inherently Chiral Calixarenes: Synthesis and Applications

Abstract

This article looks at the chemistry surrounding the concept of inherently chiral calixarenes (ICCs), whose synthesis and application have only recently being realised. One challenge in the area of ICC chemistry is the sheer breadth and scope for installing different aspects of inherent chirality. The aim of this article is not to cover every known method, but rather to give the reader an overview of the main themes that have emerged in this area, including more recent additions to the literature. This overview will also touch on the very limited reports on the applications of ICCs which give a glimpse into the potential these compounds may have in future studies.

Recent applications of chiral calixarenes in asymmetric catalysis

“…In general, chirality can be introduced into the calixarene platform either by incorporation of a chiral group or by asymmetric placement of achiral substituents, creating chirality associated with form. This is termed inherent chirality [ 22 ]. Although chiral calixarenes prepared by these ways have been widely used in chiral recognition [ 23 – 24 ], the use of calixarenes in asymmetric catalysis is a new emerging area.…”

The 15th Frank Warren Organic Chemistry Conference

“…Prof. Dr. Hans‐Günther Schmalz gave an account of his group's work in the development of modular chiral P , P ‐ligands, for the enantioselective synthesis of structurally complex marine natural products . Prof. Henok Kinfe used his keynote lecture to exhibit the utility of glycals in synthetic organic chemistry for the construction of complex bioactive heterocycles, while Prof. Gareth Arnott detailed the potential of inherently chiral calixarenes and his journey toward selective derivatization of these molecules . Several further contributions from Dr. Temitope Olomola, Prof. Jack Mphahele (University of South Africa), Prof. Isaiah Ramaite (University of Venda), Dr. Parvesh Singh (University of KwaZulu‐Natal), and Dr. Mamalosi Selepe (University of Pretoria) described their recent progress in the construction of biologically relevant heterocycles.…”

“…[13,14] Prof. Henok Kinfe used his keynote lecture to exhibit the utility of glycals in synthetic organic chemistryf or the construction of complex bioactive heterocycles, [15] while Prof. GarethA rnott detailed the potentialo fi nherently chiral calixarenes and his journey toward selectived erivatization of these molecules. [16,17] Several further contributions from Dr.T emitope Olomola, Prof. Jack Mphahele (University of South Africa), [18,19]…”

Chiral Bambusurils for Enantioselective Recognition of Carboxylate Anion Guests

“…Chiral macrocyclic compounds are particularly interesting for this purpose, as they can attract enantiomeric guests with reasonable affinity, but also with enantiomeric selectivity, due to steric repulsions, which differ for both enantiomers. Among others, cyclodextrins, calixarenes, pillararenes, cucurbiturils, and crown ethers play a dominant role in enantiomer sensing. Cyclodextrins are composed from chiral α‐ d ‐glucopyranoside units; therefore, by their nature they are homochiral.…”

“…[4] Chiral macrocyclic compounds are particularly interesting for this purpose,a st hey can attract enantiomeric guests with reasonable affinity,b ut also with enantiomeric selectivity,d ue to steric repulsions, which differ for both enantiomers. Among others, cyclodextrins, [5] calixarenes, [6] pillararenes, [7] cucurbiturils, [8][9][10] and crown ethers [11] play ad ominant role in enantiomer sensing.C yclodextrins are composed from chiral a-d-glucopyranosideu nits;t herefore, by their nature they are homochiral. On the other hand, the chirality of calixarenes and crown ethers is induced via the attachment of chiral substituents or when the symmetry of the macrocycle is broken,g iving rise to inherently chiral compounds.…”