Hexameric Resorcinarene Capsule is a Brønsted Acid: Investigation and Application to Synthesis and Catalysis

Catalysis by small molecules (≤ 1000 Da, 10−9 m) capable of binding and activating substrates via attractive, noncovalent interactions has emerged as an important approach in organic and organometallic chemistry. While the canonical noncovalent interactions—including hydrogen-bonding, ion-pairing, and π-stacking—have become mainstays of catalyst design, the cation–π interaction has been comparatively underutilized in this context since its discovery in the 1980s. However, like a hydrogen bond, the cation–π interaction exhibits a typical binding affinity of several kcal/mol with substantial directionality. These properties render it attractive as a design element for the development of small-molecule catalysts, and in recent years, the catalysis community has begun to take advantage of these features, drawing inspiration from pioneering research in molecular recognition and structural biology. This review surveys the burgeoning application of the cation–π interaction in catalysis.

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“…[81] For example, triethylamine is encapsulated within the conjugate base of 89c as the dimeric ammonium ion (i.e. [Et 3 N•HNEt 3 ] + ).…”

Section: Catalyst–substrate Cation–π Interactionsmentioning

confidence: 99%

The Cation–π Interaction in Small‐Molecule Catalysis

2016

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“…At the same time, the bowl shape of monomeric cavitand molecules is controlled through intramolecular HBs between adjacent resorcinol/pyrogallol units typically expressed in solvent media such as alcohols and acetonitrile (Figure , left) . These intramolecular HB patterns suggest a similar potential for the catalytic activation of epoxides as for pyrogallol/tannic acid (Figure ) as the stabilization of key intermediate transition states through multiple HB interactions is more efficient than in the absence of such HB donors.…”

Section: Introductionmentioning

confidence: 96%

Cavitand‐Based Polyphenols as Highly Reactive Organocatalysts for the Coupling of Carbon Dioxide and Oxiranes

2016

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A variety of cavitand-based polyphenols was prepared from cheap and accessible aldehyde and resorcinol/pyrogallol reagents to give the respective resorcin[4]- or pyrogallol[4]arenes. The preorganization of the phenolic units allows intra- and intermolecular hydrogen bond (HB) networks that affect both the reactivity and stability of these HB-donor catalysts. Unexpectedly, we found that the resorcin[4]arenes show cooperative catalysis behavior compared to the parent resorcinol in the catalytic coupling of epoxides and CO2 with a significantly higher turnover. At elevated reaction temperatures, the resorcin[4]arene-based catalyst 3 d displays the best catalytic performance with very high turnover numbers and frequencies, combining increased reactivity and stability compared to pyrogallol, and an ample substrate scope. This type of polyphenol structure thus illustrates the importance of a new, highly competitive organocatalyst design to devise sustainable CO2 conversion processes.

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“…Resorcinarenes, closely related to the largely exploited calixarenes, represent a unique class of polyphenol macrocycles, which have potential use in supramolecular chemistry, catalysis, and separation science . An acid‐catalyzed condensation reaction between resorcinol and aldehyde gives a cyclic oligomer of C‐alkylresorcin[4]arene.…”

Section: Introductionmentioning

confidence: 99%

Multifaceted Supramolecular Interactions from C‐Methylresorcin[4]arene Lead to an Enhancement in In Vitro Antibacterial Activity of Gatifloxacin

Dawn

Chandra

Ade-Browne

et al. 2017

Chemistry A European J

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Mimicking the antibacterial activity of polyphenols in synthetic systems is an attractive approach for the development of new active pharmaceutical ingredients. Resorcinarenes represent a class of polyphenols, which have been exploited for decades for their attractive chemical scaffold suitable for forming host-guest complexes with hydrophobic guest molecules. However, the polyphenolic character of resorcinarenes, which could be a potential asset to the pharmaceutical industry, have been least exploited. The present work represents an unprecedented interplay of antimicrobial activity of resorcinarene together with its ability to interact chemically with an antibacterial drug gatifloxacin, improving the overall antibacterial activity. The chemistry and the clinical activities involved in this study were investigated simultaneously by spectroscopic techniques, as well as by in vitro measurement of antibacterial activity toward two human bacterial pathogens, a Gram-positive pathogen Staphylococcus aureus and a Gram-negative lung pathogen Legionella pneumophila. The initial positive result obtained from this study could revolutionize the use of synthetically modifiable resorcinarenes and their analogues in fine tuning the clinical behavior of drugs.

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Hexameric Resorcinarene Capsule is a Brønsted Acid: Investigation and Application to Synthesis and Catalysis

Cited by 171 publications

References 86 publications

The Cation–π Interaction in Small‐Molecule Catalysis

The Cation–π Interaction in Small‐Molecule Catalysis

Cavitand‐Based Polyphenols as Highly Reactive Organocatalysts for the Coupling of Carbon Dioxide and Oxiranes

Multifaceted Supramolecular Interactions from C‐Methylresorcin[4]arene Lead to an Enhancement in In Vitro Antibacterial Activity of Gatifloxacin

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