Photochemistry of 1,1,2,2-tetraphenylethane. Di-.pi.-ethane reaction

Binkley, Roger W.; Schumann, William C.; Vashi, D. B.; Ross, James A.

doi:10.1021/jo00966a006

Cited by 8 publications

(3 citation statements)

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“…Analytical data for 5a , 6f , 6 g , and trimethylsilyldiphenylmethane agreed with literature values. − In the case of 5a , the synthetic pathway involves a Barbier reaction of the appropriate benzophenone with the bromodiphenylmethane followed by a dehydration reaction in acidic conditions, as reported in the Supporting Information.…”

Section: Methodssupporting

confidence: 80%

“…[43][44][45] In the case of 5a, the synthetic pathway involves a Barbier reaction of the appropriate benzophenone with the bromodiphenylmethane followed by a dehydration reaction in acidic conditions, as reported in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

“…The product was purified by flash column chromatography on silica gel using hexanes as eluant to afford 360 mg of a white solid: yield 50.0%; mp 124-126 °C; 1 Analytical data for 5a, 6f, 6g, and trimethylsilyldiphenylmethane agreed with literature values. [43][44][45] In the case of 5a, the synthetic pathway involves a Barbier reaction of the appropriate benzophenone with the bromodiphenylmethane followed by a dehydration reaction in acidic conditions, as reported in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

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Dications of Fluorenylidenes. The Relationship between Redox Potentials and Antiaromaticity for Meta- and Para-Substituted Diphenylmethylidenefluorenes

et al. 2005

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[reaction: see text] Electrochemical oxidation of meta-substituted diphenylmethylidenefluorenes (3a-g) results in the formation of fluorenylidene dications that are shown to be antiaromatic through calculation of the nucleus independent chemical shift (NICS) for the 5- and 6-membered rings of the fluorenyl system. There is a strong linear correlation between the redox potential for the dication and both the calculated NICS and sigma(m). Redox potentials for formation of dications of analogously substituted tetraphenylethylenes shows that, with the exception of the p-methyl derivative, the redox potentials for these dications are less positive than for formation of the dications of 3a-g and for dications of p-substituted diphenylmethylidenefluorenes, 2a-g. The greater instability of dications of 2a-g and 3a-g compared to the reference system implies their antiaromaticity, which is supported by the positive NICS values. The redox potentials for formation of the dications of meta-substituted diphenylmethylidenes (3a-g) are more positive than for the formation of dications of para-substituted diphenylmethylidenes (2a-g), indicating their greater thermodynamic instability. The NICS values for dications of 3a-g are more antiaromatic than for dications of 2a-g, which is consistent with their greater instability of the dications of 3a-g. Although the substituted diphenylmethyl systems are not able to interact with the fluorenyl system through resonance because of their geometry, they are able to moderate the antiaromaticity of the fluorenyl cationic system. Two models have been suggested for this interaction, sigma to p donation and the ability of the charge on the substituted ring system to affect delocalization. Examination of bond lengths shows very limited variation, which argues against sigma to p donation in these systems. A strong correlation between NICS and sigma constants suggests that factors that affect the magnitude of the charge on the benzylic (alpha) carbon of the diphenylmethyl cation affect the antiaromaticity of the fluorenyl cation. Calculated atomic charges on carbons 1-8 and 10-13 show an increase in positive charge, and therefore greater delocalization of charge in the fluorenyl system, with increasing electronegativity of the substituent. The change in the amount of positive charge correlated strongly with NICS, supporting the model in which the amount of delocalization of charge is related to the antiaromaticity of the species. Thus, both aromatic and antiaromatic species are characterized by extensive delocalization of electron density.

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Section: Methodssupporting

confidence: 80%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Dications of Fluorenylidenes. The Relationship between Redox Potentials and Antiaromaticity for Meta- and Para-Substituted Diphenylmethylidenefluorenes

et al. 2005

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Photochemische Umlagerungen und Fragmentierungen von Benzol-Derivaten und anellierten Arenen

Kaupp

1980

Angew. Chem.

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In diesem Aufsatz werden die zahlreichen, haufig nur in der Originalliteratur genannten intramolekularen Reaktionen elektronisch angeregter Benzolderivategeordnet nach Reaktionstypensystematisch analysiert. Es konnen alle bekannten Reaktionstypen beriicksichtigt werden. Sie gliedern sich in Reaktionen des Benzolrings (Ionisierung, Ringoffnung, Ringveranderung), Reaktionen mit Seitenkettenbeteiligung (a-, @-, y-Spaltungen, Homolyse, Heterolyse), Reaktionen von Substituenten mit Seitenketten (Cyclisierung, Entalkylierung, Schutzgruppenabspaltung) und Reaktionen von Seitenketten mit dem aromatischen Ring (Substitution, Addition, Entaromatisierung, Cyclisierung). Die Wahl zwischen energetisch moglichen konkurrierenden Reaktionen wird iiberwiegend von geometrischen Faktoren bestimmt. Die Anwendungen der empirischen Effekte in der praparativen Chemie sind sehr vielseitig. Zahlreiche hier besprochene Reaktionen werden bereits industriell ausgewertet (2. B. in der Photochromie, UV-Stabilisierung, Photographie, Informationsspeicherung, Druck-, Lackierungs-und Polymertechnologie sowie Pharmazie).

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Eine neue Photoreaktion von γ,δ‐ungesättigten Ketonen: die Oxadi‐π‐ethan(ODPE)‐Umlagerung

Leitich

Schaffner

1993

Angewandte Chemie

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Nur die intramolekulare [2 + 2]‐Cycloaddition zu Oxetanen 2 war bisher als Photoreaktion von Ketonen des Typs 1 bekannt ‐ unter Umständen ist jedoch auch eine Photoisomerisierung zu den Verbindungen 3 möglich, die mit einer neuartigen nichtallylischen 1,3‐Wanderung einer Acylgruppe unter Bildung eines gespannten Ringgerüsts einhergeht. Substituenten beispielsweise A = H; B,C = (CH2)4;R = Me.

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Photochemistry of 1,1,2,2-tetraphenylethane. Di-.pi.-ethane reaction

Cited by 8 publications

References 0 publications

Dications of Fluorenylidenes. The Relationship between Redox Potentials and Antiaromaticity for Meta- and Para-Substituted Diphenylmethylidenefluorenes

Dications of Fluorenylidenes. The Relationship between Redox Potentials and Antiaromaticity for Meta- and Para-Substituted Diphenylmethylidenefluorenes

Photochemische Umlagerungen und Fragmentierungen von Benzol-Derivaten und anellierten Arenen

Eine neue Photoreaktion von γ,δ‐ungesättigten Ketonen: die Oxadi‐π‐ethan(ODPE)‐Umlagerung

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