Regioselective <i>O</i>-Substitution of <i>C</i>-Undecylresorcin[4]arene

Farina, Francesco; Talotta, Carmen; Gaeta, Carmine; Neri, Placido

doi:10.1021/ol201919p

“…From an analytical point of view, the stereochemical characterization was achieved after resolution of the racemic mixture by preparative enantioselective high-performance liquid chromatography (eHPLC) followed by off-line optical rotatory dispersion (ORD) and electronic circular dichroism (ECD) spectroscopic analysis on the two collected enantiomeric fractions. As an extension of that work, the present investigation will focus on the determination of the AC of five O -functionalized resorcin[4]arenes, which have been synthesized by weak-base-promoted O -alkylation of C -undecylresorcin[4]arene . The AC will be assessed by comparison between their experimental ECD spectra and those determined by DFT and semiempirical calculations; an interpretation of the results in terms of the exciton chirality model (ECM) will also be given.…”

Section: Introductionmentioning

confidence: 99%

Absolute Configuration Assignment of Chiral Resorcin[4]arenes from ECD Spectra

Concilio

¹

,

Talotta

²

,

Gaeta

³

et al. 2016

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Racemates of five chiral resorcin[4]arenes, four tetra-O-substituted and one hepta-O-substituted, have been resolved by enantioselective HPLC, and their ECD spectra have been recorded online by stopped-flow measurements. The absolute configuration has been assigned by comparison of the experimental ECD spectra with DFT and semiempirical calculations. For the four tetra-O-substituted resorcin[4]arenes, the ECD exciton couplet at longer wavelength depends on the chirality induced in the arene scaffold by the substituents rather than on the precise nature of the substituents themselves. Accordingly, the exciton chirality model with excitons localized on the arene scaffold, here generalized to C symmetry, accurately describes the relationship between stereochemistry and chiroptical properties for this couplet, while its application at shorter wavelengths is unsafe. For the significantly larger hepta-O-substituted system the assignment particularly benefits from the use of the semiempirical ZINDO method.

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“…It is worth addressing that the formation of products 10 and 11 from reactant 1 indicated the site‐selective sextuple methylation reaction of 1 though twelve phenolic hydroxyl groups were amenable to react. The formation of an intramolecular hydrogen bond between hydroxyl and methoxy moieties was mainly responsible to prevent the second methylation from happening in each fjord of resorcin[6]arene 1 …”

Section: Figurementioning

confidence: 99%

Construction of Hydrocarbon Nanobelts

Shi

¹

,

Tong

²

,

Wang

³

2020

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Linearly fused hydrocarbon nanobelts are a unique type of double‐stranded macrocycles that would serve as not only the powerful hosts in supramolecular science but also the templates to grow zig‐zag carbon nanotubes with defined diameters. Fully conjugated hydrocarbon nanobelts such as belt[n]arenes would also possess unique physical and chemical properties. Despite the importance, both fully conjugated and (partially) saturated hydrocarbon nanobelts remain largely unexplored because of the lack of cyclization methods. Reported here is the construction of nanometer sized H12‐belt[12]arenes based on the strategy to close up all fjords of resorcin[6]arene by means of six‐fold intramolecular alkylation reactions of resorcin[6]arene derivatives. All resulting H12‐belt[12]arenes produce a very similar nanobelt core structure with six benzene rings and six boat 1,4‐cyclohexadiene rings being alternately linear‐fused to give a nearly equilateral hexagonal cylinder. The average long diagonal is around 1 nm and the height of the cylinder is about 0.3 nm. The acquired H12‐belt[12]arenes would be the potential precursors to various hydrocarbon nanobelts including fully conjugated belt[12]arenes.

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“…The formation of an intramolecular hydrogen bond between hydroxyl and methoxy moieties was mainly responsible to prevent the second methylation from happening in each fjord of resorcin [6]arene 1. [27] Having pure intermediates in hand, we embarked the synthesis of hydrocarbon nanobelt molecule 14 first from 10 because of its higher molecular symmetry than 11. The Suzuki coupling reaction of 10 with a boron reagent produced propenyl-substituted resorcin [6]arene 12 in 69 % yield.…”

Section: Angewandte Chemiementioning

confidence: 99%

Construction of Hydrocarbon Nanobelts

Shi

¹

,

Tong

²

,

Wang

³

2020

View full text Add to dashboard Cite

Linearly fused hydrocarbon nanobelts are a unique type of double‐stranded macrocycles that would serve as not only the powerful hosts in supramolecular science but also the templates to grow zig‐zag carbon nanotubes with defined diameters. Fully conjugated hydrocarbon nanobelts such as belt[n]arenes would also possess unique physical and chemical properties. Despite the importance, both fully conjugated and (partially) saturated hydrocarbon nanobelts remain largely unexplored because of the lack of cyclization methods. Reported here is the construction of nanometer sized H12‐belt[12]arenes based on the strategy to close up all fjords of resorcin[6]arene by means of six‐fold intramolecular alkylation reactions of resorcin[6]arene derivatives. All resulting H12‐belt[12]arenes produce a very similar nanobelt core structure with six benzene rings and six boat 1,4‐cyclohexadiene rings being alternately linear‐fused to give a nearly equilateral hexagonal cylinder. The average long diagonal is around 1 nm and the height of the cylinder is about 0.3 nm. The acquired H12‐belt[12]arenes would be the potential precursors to various hydrocarbon nanobelts including fully conjugated belt[12]arenes.

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Regioselective O-Substitution of C-Undecylresorcin[4]arene

Cited by 12 publications

References 47 publications

Absolute Configuration Assignment of Chiral Resorcin[4]arenes from ECD Spectra

Absolute Configuration Assignment of Chiral Resorcin[4]arenes from ECD Spectra

Construction of Hydrocarbon Nanobelts

Construction of Hydrocarbon Nanobelts

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