7,7-Diphenylnorbornane: The first cofacial diphenylmethane derivative

Martı́nez, Antonio Garcı́a; Barcina, José Osío; Albert, Armando; Cano, F. H.; Subramanian, L. R.

doi:10.1016/s0040-4039(00)61693-3

Cited by 12 publications

(7 citation statements)

References 13 publications

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“…In these conformations, there are neither CT nor homoconjugative interactions between both rings. The barrier for the rotation (17.0 kcal/mol) is higher than that calculated for 7,7-diphenylnorbornane (12.5 kcal/mol) 3 Relative energy vs torsion angle (φ) of the significant conformations of 5aa . …”

Section: Resultsmentioning

confidence: 83%

“…We have synthesized the series of 7,7-diarylnorbornanes 5aa , 5ca , 5ac , 5da , 5dc , 5ec , and 5cc by successive coupling of the two aryl units starting from 7-norbornanone ( 1 ), according to Scheme 1. This procedure is more versatile than the uncatalyzed Friedel−Crafts reaction of 7,7-bis(triflyloxy)norbornane with benzene derivatives, our first approach to the 7,7-diphenylnorbornane system …”

Section: Resultsmentioning

confidence: 99%

“…The 7,7-diarylnorbornane system (Scheme 1) is an interesting substrate to gain further knowledge of noncovalent as well as homoconjugative interactions between aromatic molecules. The aryl groups of the more stable conformation of 7,7-diphenylnorbornane ( 6 ) adopt a peculiar face-to-face arrangement, which can be designed as apical homoconjugated. In contrast with this, the disposition in triptycenes and related compounds can be named lateral homoconjugated.…”

Section: Introductionmentioning

confidence: 99%

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Hindered Rotation in Diphenylmethane Derivatives. Electrostatic vs Charge-Transfer and Homoconjugative Aryl−Aryl Interactions

et al. 1998

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A series of p,p‘-disubstituted 7-phenyl-7-(2-fluorophenyl)norbornanes 5xy has been prepared, and the barrier (ΔG #) to 160° libration around the 2-fluoroaryl-norbornane bond has been measured by DNMR. There is spectroscopic evidence of strong homoconjugative and charge-transfer (CT) interactions between both aryl groups of 5xy. However, the relationship between ΔG # and the nature of the substituents X and Y is accounted for only by electrostatic interactions between both aryl groups in the ground state as well as in the transition state of the libration. Therefore, the notion of CT and aromatic homoconjugation as strong attractive forces between aryl groups should be definitively rejected.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hindered Rotation in Diphenylmethane Derivatives. Electrostatic vs Charge-Transfer and Homoconjugative Aryl−Aryl Interactions

et al. 1998

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“…Homoconjugation is a consequence of p-orbital overlap between isolated π-electron systems due to particular geometric situations, as schematically illustrated in Figure 1b for PPM. This type of conjugation is rare but established and has been identified so far mainly in low molar mass units [9,10,11,12,13,14,15,16,17], among others also in diphenylmethane [18,19], which can be considered as the simplest low molar mass analogue to PPM.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of High Molar Mass Poly(phenylene methylene) Catalyzed by Tungsten(II) Compounds

et al. 2018

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Poly(phenylene methylene)s (PPMs) with high molar masses were isolated by polymerization of benzyl chloride catalyzed with tungsten(II) compounds and subsequent fractionation. Four different tungsten(II) catalysts were successfully exploited for the polymerization, for which a strict temperature profile was developed. The PPMs possessed roughly a trimodal molar mass distribution. Simple fractionation by phase separation of 2-butanone solutions allowed to effectively segregate the products primarily into PPM of low molar mass (Mn = 1600 g mol−1) and high molar mass (Mn = 167,900 g mol−1); the latter can be obtained in large quantities up to 50 g. The evolution of the trimodal distribution and the monomer conversion was monitored by gel permeation chromatography (GPC) and 1H NMR spectroscopy, respectively, over the course of the polymerization. The results revealed that polymerization proceeded via a chain-growth mechanism. This study illustrates a new approach to synthesize PPM with hitherto unknown high molar masses which opens the possibility to explore new applications, e.g., for temperature-resistant coatings, fluorescent coatings, barrier materials or optical materials.

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“…Derivatives of 7,7-diaryl norbornanes have been shown to adopt a face-to-face conformation (apical cofacial) of the two aromatic substituents, the opposite conformation of the diarylmethane derivatives where the aromatic rings are nearly orthogonal and display a propeller-like disposition . In a number of such diaryl norbornanes, bearing a fluorine atom in the ortho position of the phenyl group, the rotational barriers about the 2-fluorophenyl to norbornane bond were determined by dynamic NMR spectroscopy .…”

Section: Introductionmentioning

confidence: 99%

Conformational Studies by Dynamic NMR. 93.¹ Stereomutation, Enantioseparation, and Absolute Configuration of the Atropisomers of Diarylbicyclononanes

Casarini¹,

Rosini²,

Grilli³

et al. 2003

J. Org. Chem.

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The structure of 9-(4-methoxyphenyl)-9-(3-methylphenyl) bicyclo[3.3.1]nonane (1) has been determined by single-crystal X-ray diffraction, and the rotation barriers about the two aryl-C9 bonds have been measured by variable temperature NMR spectroscopy in solution. In the case of 9-(4-methoxyphenyl)-9-(1-naphthyl)bicyclo[3.3.1]nonane (3), the barrier involving the naphthyl-C9 rotation was found to be so high as to allow the physical separation of the two atropisomers by enantioselective HPLC at ambient temperature: the absolute configuration could be established on the basis of the corresponding CD spectra. It was also observed that the Ar-C9 rotation barriers of monoaryl-substituted nonanes are much lower than those of the corresponding diaryl-substituted nonanes.

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7,7-Diphenylnorbornane: The first cofacial diphenylmethane derivative

Cited by 12 publications

References 13 publications

Hindered Rotation in Diphenylmethane Derivatives. Electrostatic vs Charge-Transfer and Homoconjugative Aryl−Aryl Interactions

Hindered Rotation in Diphenylmethane Derivatives. Electrostatic vs Charge-Transfer and Homoconjugative Aryl−Aryl Interactions

Synthesis of High Molar Mass Poly(phenylene methylene) Catalyzed by Tungsten(II) Compounds

Conformational Studies by Dynamic NMR. 93.¹ Stereomutation, Enantioseparation, and Absolute Configuration of the Atropisomers of Diarylbicyclononanes

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7,7-Diphenylnorbornane: The first cofacial diphenylmethane derivative

Cited by 12 publications

References 13 publications

Hindered Rotation in Diphenylmethane Derivatives. Electrostatic vs Charge-Transfer and Homoconjugative Aryl−Aryl Interactions

Hindered Rotation in Diphenylmethane Derivatives. Electrostatic vs Charge-Transfer and Homoconjugative Aryl−Aryl Interactions

Synthesis of High Molar Mass Poly(phenylene methylene) Catalyzed by Tungsten(II) Compounds

Conformational Studies by Dynamic NMR. 93.1 Stereomutation, Enantioseparation, and Absolute Configuration of the Atropisomers of Diarylbicyclononanes

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Conformational Studies by Dynamic NMR. 93.¹ Stereomutation, Enantioseparation, and Absolute Configuration of the Atropisomers of Diarylbicyclononanes