Electron-Transfer Photochemistry of<i>cis</i>- and<i>trans</i>-1,2-Diphenylcyclopropane with Singlet Acceptors:  Recombination of Radical Ion Pairs of Singlet and Triplet Multiplicity

Roth, Heinz D.

doi:10.1021/jp026902z

Cited by 10 publications

(4 citation statements)

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“…For another perspective, we examined the results of intramolecular competition experiments with para -substituted 1,2-diphenylcyclopropanes. The structures of an array of arylcyclopropane radical cations have been studied extensively both computationally and spectroscopically; , although some arylcyclopropanes exhibit closed radical cation geometries, diarylcyclopropanes have been determined to be open . Our idea was that substituted diarylcyclopropanes, with the possibility of open geometries, could display divergent behavior in a Hammett plot.…”

Section: Introductionmentioning

confidence: 99%

“…Arylcyclopropane radical cation intermediates have been accessed and studied by electron transfer quenching of the excited states of various singlet or triplet acceptors (e.g., 1,4-dicyanonaphthalene, 1-cyanonaphthalene, 1,4-dicyanobenzene, 1,2,4,5-tetracyanobenzene, 9-cyanophenanthrene, chloranil, and 3,3′,4,4′-benzophenonetetracarboxylic anhydride) . The formation of radical ion pairs between arylcyclopropanes and these photosensitizers by photoinduced electron transfer (PET) is typically guided by the excited state of the electron acceptor, which makes this aminofluorination reaction unique.…”

Section: Introductionmentioning

confidence: 99%

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Aminofluorination of Cyclopropanes: A Multifold Approach through a Common, Catalytically Generated Intermediate

et al. 2016

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We have discovered a highly regioselective aminofluorination of cyclopropanes. Remarkably, four unique sets of conditions-two photochemical, two purely chemical-generated the same aminofluorinated adducts in good to excellent yields. The multiple, diverse ways in which the reaction could be initiated provided valuable clues that led to the proposal of a "unifying" chain propagation mechanism beyond initiation, tied by a common intermediate. In all, the proposed mechanism herein is substantiated by product distribution studies, kinetic analyses, LFERs, Rehm-Weller estimations of ΔGET, competition experiments, KIEs, fluorescence data, and DFT calculations. From a more physical standpoint, transient-absorption experiments have allowed direct spectroscopic observation of radical ion intermediates (previously only postulated or probed indirectly in photochemical fluorination systems) and, consequently, have provided kinetic support for chain propagation. Lastly, calculations suggest that solvent may play an important role in the cyclopropane ring-opening step.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aminofluorination of Cyclopropanes: A Multifold Approach through a Common, Catalytically Generated Intermediate

et al. 2016

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“…With the insights gained from the studies of cyclic alkene isomerization discussed above, Inoue revisited the asymmetric isomerization of 1,2-diarylcyclopropanes originally reported by Hammond . Several arenecarboxylate sensitizers were tested, but the highest reported ee for trans - 1 was 10%. − …”

Section: Organic Chromophoresmentioning

confidence: 99%

Chiral Photocatalyst Structures in Asymmetric Photochemical Synthesis

et al. 2021

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Asymmetric catalysis is a major theme of research in contemporary synthetic organic chemistry. The discovery of general strategies for highly enantioselective photochemical reactions, however, has been a relatively recent development, and the variety of photoreactions that can be conducted in a stereocontrolled manner is consequently somewhat limited. Asymmetric photocatalysis is complicated by the short lifetimes and high reactivities characteristic of photogenerated reactive intermediates; the design of catalyst architectures that can provide effective enantiodifferentiating environments for these intermediates while minimizing the participation of uncontrolled racemic background processes has proven to be a key challenge for progress in this field. This review provides a summary of the chiral catalyst structures that have been studied for solution-phase asymmetric photochemistry, including chiral organic sensitizers, inorganic chromophores, and soluble macromolecules. While some of these photocatalysts are derived from privileged catalyst structures that are effective for both ground-state and photochemical transformations, others are structural designs unique to photocatalysis and offer insight into the logic required for highly effective stereocontrolled photocatalysis.

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“…59 Photoinduced electron transfer from cis-and trans-1,2-diphenylcyclopropane to chloranil, 1,4-dicyanonaphthalene or 9-cyanoanthracene acceptors gives radical ion pairs which can undergo back electron transfer. 60…”

Section: Scheme 30 Scheme 31 8 Photoinduced Electron Transfermentioning

confidence: 99%