Substituent effects and the di-.pi.-methane rearrangement. Mechanistic and exploratory organic photochemistry

Zimmerman, Howard E.; Cotter, Bryon R.

doi:10.1021/ja00831a012

Cited by 18 publications

(11 citation statements)

References 11 publications

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“…12 Conversely, in Scheme 14, the enol ether methoxyl group is found on the surviving double bond of photoproduct. 12 In Scheme 15 the p-cyanophenyl groups are found on the three-membered ring of photoproduct 13 while the (N,N-dimethylamino)phenyl groups remain on the double bond of product. 14 A further question occurs when there are three π-systems bonded to a single "methane carbon".…”

Section: Reaction Regioselectivitymentioning

confidence: 99%

Synthetic Aspects of the Di-π-methane Rearrangement

1996

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Section: Reaction Regioselectivitymentioning

confidence: 99%

Synthetic Aspects of the Di-π-methane Rearrangement

1996

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“…Although 2b 6 is a known compound we were unable to find NMR characterizations. For compound 2j 7,8 we did not find adequate 13 C or 1 H NMR characterizations. Lacking elementary analysis and spectral data are complemented.…”

Section: General Methods For Synthesis Of Diaryl Ketones Frommentioning

confidence: 75%

Ultrafast Chemistry: Cobalt Carbonyl Mediated Synthesis of Diaryl Ketones under Microwave Irradiation.

2004

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Polyphenylalkane derivativesPolyphenylalkane derivatives Q 0720Ultrafast Chemistry: Cobalt Carbonyl Mediated Synthesis of Diaryl Ketones under Microwave Irradiation. -Cobalt-mediated, microwave-heated carbonylation to prepare benzophenones from aryl iodides is developed. The method does not need either an external source of carbon monoxide gas nor strong base or an oxidating agent. The reaction proceeds within 6-10 s and provides the ketones in high yields. -(ENQUIST, P.-A.; NILSSON, P.; LARHED*, M.; Org. Lett. 5 (2003) 25, 4875-4878; Dep. Med. Chem., Uppsala Univ., S-751 23 Uppsala, Swed.; Eng.) -Steudel 16-101

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“…The small effect of the solvent polarity on ΦCP.2 seems to indicate that the excited state surface leading to the 1,2-photomigration of H has a more accentuated radical character. The pathway on this surface should not be affected by the motions leading to the surface corresponding to the di-π-methane rearrangement ("touching" motion between both π moieties 25 ). On the surface leading to the CP.1 formation, the charge transfer complex in the excited state is stabilized by polar solvents, decreasing the formation rate of this cyclopropane.…”

Section: Discussionmentioning

confidence: 99%

The photochemical reaction of 1,1-dicyano-3-phenylbut-1-ene. Simultaneous occurrence of pi-methane and di-pi-methane rearrangements

Silva¹,

Ferreira²,

Neumann³

1999

J. Braz. Chem. Soc.

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A fotólise direta de 1,1-diciano-3-fenilbutene-1 (3-MDCN) foi pesquisada a temperatura ambiente em solventes de diferentes polaridades (hexano, diclorometano e acetonitrilo). Foram obtidos fotoprodutos originários dos processos di-π-metano e π-metano (migração de hidrogênio 1,2). As estruturas dos produtos foram determinadas por 1 H-NMR, GC/MS, IV e cromatografia. Os resultados das determinações dos rendimentos quânticos relativos e as análises cromatográficas de irradiações sequênciais evidenciaram que i) não ocorrem reações secundárias, até a altas conversões; ii) o rearranjo di-π-metano é mais afetado pelas variações de solvente que o rearranjo π-metano. Não foram observados produtos por fotosensitização com acetofenona ou acetona. A presença de mecanismo simultâneos e os efeitos de solvente foram considerados como evidência de excitações localizadas e deslocalizadas sobre a superfície de energia potencial.The direct photolysis of 1,1-dicyano-3-phenylbut-1-ene (3-MDCN) was investigated at room temperature in solvents of different polarities (hexane, dichloromethane and acetonitrile). Cyclopropanes arising from both the di-π-methane and π-methane (1,2-H migration) processes were obtained as photoproducts. The structures of the products were elucidated by 1 H-NMR, GC/MS, IR and chromatography. Relative quantum yield determination and GC analysis of sequential irradiations gave evidence that: i) no secondary reactions occur, even at high conversions; ii) the di-π-methane rearrangement is significantly more affected by the solvent variation than the π-methane reaction. Photosensitization with acetophenone or acetone did not yield any observable products. The existence of the simultaneous mechanisms and the observed effects were considered as evidence of a possible differentiation between localized and delocalized excitation on the excited state surface.

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Substituent effects and the di-.pi.-methane rearrangement. Mechanistic and exploratory organic photochemistry

Cited by 18 publications

References 11 publications

Synthetic Aspects of the Di-π-methane Rearrangement

Synthetic Aspects of the Di-π-methane Rearrangement

Ultrafast Chemistry: Cobalt Carbonyl Mediated Synthesis of Diaryl Ketones under Microwave Irradiation.

The photochemical reaction of 1,1-dicyano-3-phenylbut-1-ene. Simultaneous occurrence of pi-methane and di-pi-methane rearrangements

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