Azacalixphyrin: The Hidden Porphyrin Cousin Brought to Light

Chen, Zhongrui; Giorgi, Michel; Jacquemin, Denis; Elhabiri, Mourad; Siri, Olivier

doi:10.1002/ange.201301217

Cited by 13 publications

(18 citation statements)

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“…331 An aromatic porphyrinoid (724) with four benzene subunits has been reported (Scheme 236), although this system is connected by nitrogen bridges. 332,333 Azacalix [4]arene 725a was prepared by subjecting 1,3-difluoro-4,6-dinitrobenzene to a series of nucleophilic addition−elimination reactions with 1,2,4,5-tetraaminobenzene. The nitro groups were reduced with hydrogen over palladium−charcoal to give octaaminoazacalixarene 725b, and subsequent air oxidation afforded the aromatic system azacalixphyrin 724.…”

Section: Tri-and Tetracarbaporphyrinoidsmentioning

confidence: 99%

“…Although 724 can be considered to be a tetracarbaporphyrinoid system, albeit with aza-linkages, it is very different from quatyrin, the hypothetical hydrocarbon analogue of the porphyrins. 332 15. EXPANDED CARBAPORPHYRINOID SYSTEMS following oxidation with DDQ, benzocarbasapphyrin 727 was isolated in 18% yield (Scheme 237).…”

Section: Tri-and Tetracarbaporphyrinoidsmentioning

confidence: 99%

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Carbaporphyrinoid Systems

2016

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Following immediately after the serendipitous discovery of N-confused porphyrins, remarkably diverse carbaporphyrinoid systems have been synthesized and investigated. By replacing a pyrrolic unit within the porphyrin framework with cyclopentadiene, indene, azulene, cycloheptatriene, or benzene, new families of porphyrin-like macrocycles were produced. True carbaporphyrins are fully aromatic structures, while benziporphyrins are essentially devoid of macrocyclic aromatic character, and azuliporphyrins fall midway between the two extremes. Monocarbaporphyrinoids are superior organometallic ligands and form stable complexes with copper(III), silver(III), gold(III), nickel(II), palladium(II), platinum(II), rhodium(III), iridium(III), and ruthenium(II). Unusual oxidation reactions have also been discovered, commonly leading to derivatization of the internal carbon atom. In addition, structural rearrangements have been uncovered that allow the conversion of azuliporphyrins into benzocarbaporphyrins, and benziporphyrins into carbaporphyrins. Although less well studied, many examples of dicarbaporphyrinoids have been reported, and these show equally intriguing characteristics. Furthermore, contracted and expanded carbaporphyrinoids have been investigated. Studies in this area provide fundamental insights into the aromatic properties, tautomerization, and reactivity of porphyrins and related macrocyclic systems.

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Section: Tri-and Tetracarbaporphyrinoidsmentioning

confidence: 99%

Section: Tri-and Tetracarbaporphyrinoidsmentioning

confidence: 99%

Carbaporphyrinoid Systems

2016

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“…Siri et al. recently used a similar strategy to prepare the first azacalixphyrin molecule with near‐IR absorption 4…”

Section: Methodsmentioning

confidence: 99%

Stereoselective Synthesis of α‐Trifluoromethyl Enones by Au^I/Cu^I‐Co‐Catalyzed Tandem 1,3‐Acyloxy Migration/Trifluoromethylation Reaction of Propargyl Acetates

Lin

Xiao

et al. 2014

Eur J Org Chem

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Dihydroxybenziphthalocyanine 1, with bulky aryloxy groups, has been synthesized and characterized by X‐ray crystallography, NMR and UV/Vis‐NIR spectroscopy, and theoretical calculations. Macrocycle 1 is the first example of an aromatic benziphthalocyanine with an 18π‐electron structure, and was found to exist as an equilibrium mixture of weakly aromatic and strongly aromatic tautomers. The aromaticity and near‐IR absorption can be controlled by chemical modification at the reactive resorcinol moiety and by variation of the solvent.

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“…26,27 In 2013, the azacalixphyrin (ACP, Figure 1) was reported as the only known "azacalixarene-like" derivative introducing four oxidized tetraaminobenzene units that promote a stable bis-zwitterionic ground electronic state. [28][29][30][31][32][33] Consequently ACP can be viewed as a masked conjugated azacalixquinone. Its aromatic core involving 18 π-electrons confers to the ACP a strong absorption ca.…”

Section: Introductionmentioning

confidence: 99%

Azacalixquinarenes: From Canonical to (Poly-)Zwitterionic Macrocycles

et al. 2019

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Azacalixquinarenes, a new family of macrocycles constituted of diaminobenzoquinone diimine units linked by dinitrobenzene rings are synthesized by selected oxidation of the parent azacalixarenes. Crystallographic analyses of two compounds demonstrated the presence of (uncharged) canonical and zwitterionic quinones within a single structure. The electron-withdrawing nature of the dinitrobenzene moieties can trigger the intramolecular H-transfer that generates zwitterionic-ground state quinones. The nature of the Nsubstituents and the polarity of the solvent have a crucial impact on the equilibrium between the canonical and zwitterionic forms that present distinct optical and electrochemical properties. Thus, within [4]-and [6]-membered macrocycles, poly-zwitterionic structures can be reached, as demonstrated experimentally and theoretically using first-principle approaches. With the aim to combine several of these systems in a single molecule and study the impact on the canonical/zwitterionic equilibrium, we naturally focused our attention on the elaboration of macrocyclic architectures of types 2 or 3 presenting an alternation of quinones and aromatic rings substituted with EWG. We report herein their synthesis from ACA precursors and demonstrate that these macrocycles (2a-c and 3a), named azacalixquinarenes (ACQ), can be seen as "hemi-azacalixphyrins", i.e. an intermediary class of ACA-ACP derivatives featuring an alternation of dinitrosubstituted aromatic rings and diaminobenzoquinone diimine rings. As for model compounds 1a-d, the quinoidal fragments within ACQs can be either stabilized under canonical (uncharged) or zwitterionic forms depending on given parameters (N-substituents, solvent), allowing to reach unprecedented poly-zwitterionic systems. RESULTS AND DISCUSSION Synthesis. The access to the target ACQs 2a-c was envisaged by chemical oxidation of the azacalix[4]arene precursors (Scheme 1). Therefore, the preparation of ACA 7a-c was carried out following a well-established strategy starting from precursors 4a-c, incorporating octylamine or selected aniline moieties, which were reduced under acidic conditions in presence of Sn(II) salts or Fe powder, then substituted by 1,5-difluoro-2,4-dinitrobenzene (DFDNB) to afford the adducts 6a-c. 30, 34 Scheme 1. Synthesis of compounds 1a-d, 2a-c and 3a (quinones only represented under their canonical forms). These intermediates were converted to the corresponding azacalix[4]arene 7a-c using one equivalent of tetraaminobenzenes 4a-c in refluxing acetonitrile. For compound 6d, previously unknown, the reaction was carried out at room temperature and a low concentration of 5d (10-2 M) was necessary to reach a moderate yield (43%, Table S1). Such poor efficiency is presumably imputable to a lack of regioselectivity during the nucleophilic aromatic substitution of the electron-rich adduct 5d on DFDNB. Unfortunately, for the same reason, it was impossible to reach the corresponding azacalix[4]arene 6d using classical conditions. The synthesis of azacalix[6]arenes 8a wa...

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Azacalixphyrin: The Hidden Porphyrin Cousin Brought to Light

Cited by 13 publications

References 51 publications

Carbaporphyrinoid Systems

Carbaporphyrinoid Systems

Stereoselective Synthesis of α‐Trifluoromethyl Enones by Au^I/Cu^I‐Co‐Catalyzed Tandem 1,3‐Acyloxy Migration/Trifluoromethylation Reaction of Propargyl Acetates

Azacalixquinarenes: From Canonical to (Poly-)Zwitterionic Macrocycles

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Azacalixphyrin: The Hidden Porphyrin Cousin Brought to Light

Cited by 13 publications

References 51 publications

Carbaporphyrinoid Systems

Carbaporphyrinoid Systems

Stereoselective Synthesis of α‐Trifluoromethyl Enones by AuI/CuI‐Co‐Catalyzed Tandem 1,3‐Acyloxy Migration/Trifluoromethylation Reaction of Propargyl Acetates

Azacalixquinarenes: From Canonical to (Poly-)Zwitterionic Macrocycles

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Stereoselective Synthesis of α‐Trifluoromethyl Enones by Au^I/Cu^I‐Co‐Catalyzed Tandem 1,3‐Acyloxy Migration/Trifluoromethylation Reaction of Propargyl Acetates