Funnels and barriers in the photocycloaddition of arenes to alkenes and dienes

Hart, Johanna A. van der; Mulder, J. J. C.; Cornelisse, J.

doi:10.1016/1010-6030(94)03925-k

Cited by 14 publications

(7 citation statements)

References 30 publications

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“…Earlier theoretical investigations predicted that polar transition states of similar structures are involved in both [2 + 2] and [3 + 2] photocycloadditions of alkenes to electronically excited benzene derivatives . However, a more recent theoretical study 6 indicated the intervention of nonpolar diradical intermediates rather than polar transition states but, unfortunately, could not make a plausible prediction about the competition between the branching two [2 + 2] and [3 + 2] cycloaddition pathways.…”

Section: Introductionmentioning

confidence: 99%

Novel [2 + 2] Photocycloaddition-Induced Rearrangement of Bichromophoric Naphthalene-Tethered Resorcinol Ethers

Hoffmann¹,

Pete²,

Inoue³

et al. 2002

J. Org. Chem.

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The first examples of sequential photocycloaddition-rearrangement reactions of naphthalene-tethered resorcinol ethers are described. Bichromophoric aromatic compounds with naphthalene and resorcinol ether moieties were irradiated in the presence/absence of a small amount of acid to give the corresponding cycloaddition-rearrangement products. From the determination of quantum yields, steady-state fluorescence spectral studies, and fluorescence lifetime measurements, the mechanism of this novel photoinduced multistep reaction was elucidated to involve the initial intramolecular exciplex formation, followed by the intramolecular [2 + 2] photocycloaddition between the two aromatic rings and the subsequent acid-catalyzed skeletal rearrangement of the resulting cyclobutane derivative leading to the final products.

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Section: Introductionmentioning

confidence: 99%

Novel [2 + 2] Photocycloaddition-Induced Rearrangement of Bichromophoric Naphthalene-Tethered Resorcinol Ethers

Hoffmann¹,

Pete²,

Inoue³

et al. 2002

J. Org. Chem.

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“…Alternatively, theoretical analyses of the ortho cycloaddition reaction suggest that this reaction is forbidden and that there is a barrier between the excited state of the reactants and the ultimate products. ,, It is therefore plausible that the gas- phase reaction succeeds because the vibrational energy available to the reactants allows them to pass over this barrier. This would explain why the reaction is minimal in solution or with high pressures of butane but would not explain why the reaction is unobservable in the absence of butane.…”

Section: Discussionmentioning

confidence: 99%

Photochemistry of 5-Phenyl-1-pentene in the Gas Phase

Morrison

2005

J. Am. Chem. Soc.

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The photochemistry of the title compound has been studied in the gas phase using 254-nm irradiation. In addition to meta cycloadducts analogous to those observed in solution, population of S1 vib in the gas phase gives several products, the relative amounts of which depend on quencher gas pressure but not on excitation wavelength. For example, in the absence of butane, the major photoproduct is compound 5. This product is formed by a [1,5] hydrogen shift in the primary photoproduct, compound 4. Compound 4 is an intramolecular meta cycloadduct that is generated in the gas phase with sufficient excess vibrational energy to undergo rearrangement unless quencher gas is present. Likewise, there is evidence that two other meta cycloadducts (2 and 3) are also formed with appreciable vibrational energy in the absence of a quencher gas. A unique intramolecular ortho cycloadduct is also formed from 1 but only within a narrow range of quencher gas pressures. This is a two-photon product, with the initial cycloadduct (11) ring opening to a cyclooctatriene (12) that photochemically closes to 6. The pressure dependence of this ortho cycloaddition may be due to a requirement for vibrational deactivation of 11 (Scheme ) or a precursor species (Scheme ). The overall chemistry is outlined in Scheme .

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“…Photocycloadditions of arenes with alkenes are usually triggered by the photoexcitation of the arene moiety. If the first excited singlet state of benzene is involved ( 1 B 2u , excited at 254 nm in a electric dipole forbidden transition, ε = 20.4), only the meta mode is allowed to occur in a concerted fashion according to molecular orbital symmetry rules [ 19 – 20 ]. Concerted ortho and para photocycloadditions of olefins are forbidden to occur from the first excited-state, but they are formally allowed from the second excited-state of benzene ( 1 B 1u ).…”

Section: Reviewmentioning

confidence: 99%