Conformational study of the higher [n.n]paracylophanes: evaluation as potential hosts for molecular halogens and benzenes

Mascal, Mark; Kerdelhué, Jean Luc; Batsanov, Andrei S.; Begley, Michael J.

doi:10.1039/p19960001141

Cited by 8 publications

(5 citation statements)

References 33 publications

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“…In the case of [ n . n ]paracyclophanes, an energy minimum is found when n is an odd number and the two benzene rings are in a face‐to‐face conformation 9. This is true for the [7.7]paracyclophane system, as revealed by crystallographic analysis, which is reported to be almost strain‐free.…”

Section: Resultsmentioning

confidence: 90%

Synthesis and Redox Behavior of Wurster Blue Cyclophanes

2004

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Two cyclophanes composed of two p‐phenylenediamine (PPD) units connected by methylene chains of different lengths (1c, n = 3; 2c, n = 5) have been synthesized. The PPD unit of cyclophane 1c was oxidized by a two‐electron transfer process to give 1c2+ at the first oxidation potential. In contrast, 2c was oxidized by a one‐electron transfer process to give 2c+ and then 2c2+. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Section: Resultsmentioning

confidence: 90%

Synthesis and Redox Behavior of Wurster Blue Cyclophanes

2004

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“…Dimethyl suberate (13) was reacted with MeMgBr to afford 2,9-dimethyldecane-2,9-diol (14; 86 % yield), [15] which was then treated with a concentrated aqueous HCl solution to give 2,9-dichloro-2,9-dimethyldecane (15; 91 % yield; Scheme 2). [16] Friedel-Crafts alkylation of pyrene (6) with dichloride 15 in the presence of AlCl 3 then furnished 2,9-dimethyl-2,9-bis(2-pyrenyl)decane (16; 62 % yield).…”

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confidence: 99%

1,1,8,8‐Tetramethyl[8](2,11)teropyrenophane: Half of an Aromatic Belt and a Segment of an (8,8) Single‐Walled Carbon Nanotube

2009

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Dedicated to Professor Reginald Mitchell on the occasion of his 65th birthdayCyclacenes, for example, [12]cyclacene (1; Figure 1), and cyclophenacenes, for example, cyclo [12]phenacene (2), are aromatic belts that map onto the surfaces of various fullerenes and single-walled carbon nanotubes (SWCNTs).[1] Indeed, they can be viewed as the shortest possible open-ended (uncapped) zig-zag and armchair single-walled carbon nanotubes, respectively.[1e] Although interest in the synthesis of aromatic belts, especially cyclacenes, predates the discovery of the fullerenes [2] and SWCNTs [3] by decades, [4] the discovery of SWCNTs and their homology to aromatic belts has engendered more intense synthetic and theoretical interest, not only in cyclacenes [5] and cyclophenacenes, [6] but also in related aromatic/conjugated belts. [7] Of particular interest to us are the Vögtle belts, [8] for example, 3, which are armchair SWCNT segments having a pyrenoid or rylenoid motif, depending upon ones perspective.A recurring theme in the numerous unsuccessful attempts to synthesize aromatic belts is the inability to aromatize partially saturated belt precursors. The interplay of two major energetic factors, strain and aromaticity, is at the heart of the problem.[9] The generation of a nonplanar aromatic system from a non-or partially aromatic precursor is inherently disfavored by the build-up of strain, but favored by the aromatic stabilization energy (ASE) of the aromatic system being formed. Increasing the distortion from planarity causes the strain energy to become larger and the ASE to become smaller. As a result, strain ultimately becomes dominant and aromatization, by standard methods such as the elimination of water, can become unfavorable. For example, the addition of water (2 equiv) to Schlüters "double-stranded cycle" has been calculated to be exothermic by 42.2 kcal mol À1 .[7b]Therefore, if any approach to aromatic belts is ultimately going to be successful it will not only have to target a relatively stable structural motif, but also rely upon methodology that is capable of generating highly nonplanar aromatic systems under relatively mild conditions. The valence isomerization/dehydrogenation (VID) reaction of [2.2]metacyclophane-1,9-diene (4) to give pyrene 6 is such a method (Scheme 1 a), [10] and it has been used for the synthesis of [n](2,7)pyrenophanes containing nonplanar

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“…Employing 2c also resulted in the clean formation of a single product, which precipitated from hexane solution in the course of the RCAM reaction. Recrystallization from CHCl 3 afforded a single-crystalline material in 68% yield, which proved to be the [10.10]paracyclophane 4c by X-ray diffraction analysis . The molecule resides on a crystallographic inversion center, generating a highly symmetric 28-membered ring with coplanar aromatic rings and alkyne moieties (Figure ).…”

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Preparation of Cyclophanes by Room-Temperature Ring-Closing Alkyne Metathesis with Imidazolin-2-iminato Tungsten Alkylidyne Complexes

et al. 2008

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Room-temperature ring-closing alkyne metathesis of 1,2-, 1,3-, and 1,4-bis(3-pentynyloxymethyl)benzenes has been investigated in the presence of catalytic amounts of an imidazolin-2-iminato tungsten alkylidyne complex. The m- and p-diynes selectively form the respective [10]metacyclophane or [10.10]paracyclophane, respectively, whereas a mixture of monomeric and dimeric cycloalkynes is obtained in the case of the o-diyne. DFT calculations reveal that the different selectivities can be attributed to the relative thermodynamic stability of the emerging cyclophanes.

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Conformational study of the higher [n.n]paracylophanes: evaluation as potential hosts for molecular halogens and benzenes

Cited by 8 publications

References 33 publications

Synthesis and Redox Behavior of Wurster Blue Cyclophanes

Synthesis and Redox Behavior of Wurster Blue Cyclophanes

1,1,8,8‐Tetramethyl[8](2,11)teropyrenophane: Half of an Aromatic Belt and a Segment of an (8,8) Single‐Walled Carbon Nanotube

Preparation of Cyclophanes by Room-Temperature Ring-Closing Alkyne Metathesis with Imidazolin-2-iminato Tungsten Alkylidyne Complexes

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