A hexameric resorcinarene capsule as a hydrogen bonding catalyst in the conjugate addition of pyrroles and indoles to nitroalkenes

Gambaro, Stefania; Rosa, Margherita De; Soriente, Annunziata; Talotta, Carmen; Floresta, Giuseppe; Rescifina, Antonio; Gaeta, Carmine; Neri, Placido

doi:10.1039/c9qo00224c

Cited by 29 publications

(20 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To study the role of the halogen‐bonding interaction in the activation of 3 , we conducted a quantum‐chemical investigation. To this purpose, we chose the reaction between 2 and 3 in a reduced capsule ( C R6 ) with methyl residues and ONIOM method (M06‐2X:PM6) as a representative model . The stabilization energy of the complexes calculated by the QM method suggests that the first species to enter the capsule is 5 a , followed by 3 and then 2 (Supporting Information, Table S1, entries 1, 5, 8).…”

Section: Resultsmentioning

confidence: 99%

Synergic Interplay Between Halogen Bonding and Hydrogen Bonding in the Activation of a Neutral Substrate in a Nanoconfined Space

et al. 2019

Self Cite

View full text Add to dashboard Cite

The principle of amplified halogen bonding (XB) in a small space is exploited as a catalytic tool for the activation of an XB acceptor substrate in a nanoconfined environment. The inner cavity of the resorcinarene capsule has been equipped with an XB catalyst bearing an ammonium unit acting as a Trojan horse to drive the catalyst inside the capsule. In the presence of a specific XB catalyst, the capsule is able to catalyze a Michael reaction between N‐methylpyrrole and methyl vinyl ketone. In the bulk medium in absence of the resorcinarene capsule, the XB catalyst is catalytically ineffective. Quantum‐mechanical investigations highlight that the Michael reaction proceeds through the activation of the carbonyl group by synergistically enhanced halogen/hydrogen‐bonding interactions and takes place in an open pentameric capsule.

show abstract

Section: Resultsmentioning

confidence: 99%

Synergic Interplay Between Halogen Bonding and Hydrogen Bonding in the Activation of a Neutral Substrate in a Nanoconfined Space

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The container CR 6 shows some features that make it a useful tool in biomimetic catalysis: 3 (a) the internal π···electron-rich cavity of 1375 Å 3 is able to recognize neutral and cationic species and to stabilize transition states, due to secondary interactions; (b) the capsule CR 6 behaves as a mild Brønsted acid with a p K a value of about 5.5–6.0; 18a (c) four bridging water molecules show a H-bond-donating free valence, which is catalytically relevant. 18b , 19 In addition, previously reported data 20 show that the CR 6 capsule is able to exert a substrate selectivity, whereas stereo- and regioselectivity toward the products are also generally observed.…”

Section: Introductionmentioning

confidence: 87%

Kinetic and Thermodynamic Modulation of Dynamic Imine Libraries Driven by the Hexameric Resorcinarene Capsule

et al. 2020

Self Cite

View full text Add to dashboard Cite

The composition of dynamic covalent imine libraries (DCL) adapts to the presence of the hexameric resorcinarene capsule. In the presence of the self-assembled capsule, a kinetic and thermodynamic modulation of the imine constituents of the DCLs was observed, which was induced by an unusual predatory action of the capsule on specific imine constituents. More complex 2 × 2 DCLs also adapt to the presence of the hexameric capsule, showing a thermodynamic and kinetic modulation of the constituents induced by the predatory action of the capsule. By cross-referencing experimental data, a good selectivity (up to 66%) for one constituent can be induced in a 2 × 2 DCL.

show abstract

“…The catalytically relevant role of the bridging water molecules of C R was also demonstrated in the conjugate addition of N ‐methylpyrrole 54 (and indoles) to nitroalkenes (Scheme 18). [45] When the reaction between 54 and β ‐nitrostyrene 58 (Scheme 18) was performed in the absence of capsule in water saturated CDCl 3 no hint of products 59 a / 59 b was detected. Differently, the products 59 a / 59 b were obtained in 94 % yield (total) in the presence of capsule C R , and also in this case QM‐calculations highlighted the crucial role played by H‐bonding interactions involving the bridging water molecules in the activation of the electrophile 58 .…”

Section: Supramolecular Catalysis In Confined Spacementioning

confidence: 99%

“… Conjugate addition of N ‐methylpyrrole 54 to nitroalkene 58 in the presence of C R [45] . Inset: H‐bonding interaction between a capsular water molecules and the substrate 58 .…”

Section: Supramolecular Catalysis In Confined Spacementioning

confidence: 99%

Supramolecular Catalysis with Self‐Assembled Capsules and Cages: What Happens in Confined Spaces

et al. 2020

Self Cite

View full text Add to dashboard Cite

The confined space inside self‐assembled capsules or cages provides a unique environment in which organic reactions can be efficiently catalyzed, thanks to the confinement effect of the substrates. In confined spaces the chemical reactions can show unusual mechanisms due to the conformational control of the substrates, steric constrictions, stabilization of species by secondary interactions, and solvent exclusion. Consequently, the classical rules of the organic reactivity are often broken. Thus, many examples reported to data in the literature confirm the paradigm stated by D. J. Cram in 1989: “These carceplexes represent a new state of matter whose interiors are new phase…”. The confined space inside the self‐assembled capsules or cages represents a new phase for the chemical reactivity where there is still so much to explore. In this review we highlight the best‐known cases of reactivity in confined spaces, focusing our attention on the driving forces that drive the encapsulated reactions toward uncommon outcomes. Literature examples that constitute the landmarks in the topic of supramolecular catalysis in confined spaces are also reviewed.

show abstract

A hexameric resorcinarene capsule as a hydrogen bonding catalyst in the conjugate addition of pyrroles and indoles to nitroalkenes

Abstract: A hexameric resorcinarene capsule (C) acts as a hydrogen bonding catalyst for the addition of nitroalkenes to pyrroles and indoles.

Cited by 29 publications

References 58 publications

Synergic Interplay Between Halogen Bonding and Hydrogen Bonding in the Activation of a Neutral Substrate in a Nanoconfined Space

Synergic Interplay Between Halogen Bonding and Hydrogen Bonding in the Activation of a Neutral Substrate in a Nanoconfined Space

Kinetic and Thermodynamic Modulation of Dynamic Imine Libraries Driven by the Hexameric Resorcinarene Capsule

Supramolecular Catalysis with Self‐Assembled Capsules and Cages: What Happens in Confined Spaces

Contact Info

Product

Resources

About