1H and 13C NMR spectra of benzocyclopropenone in liquid solutions at 193 K

Simon, Jens Georg Günther; Schweig, Armin

doi:10.1016/0009-2614(93)85086-4

Cited by 13 publications

(14 citation statements)

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“…This implies that benzocyclopropenone is thermodynamically stable but is extremely reactive. The low-temperature 1 H and 13 C NMR spectra of a mixture of compounds containing benzocyclopropenone, prepared from the photochemical decarbonylation of benzocyclobutene-1,2-dione in an argon matrix at 193 K have been reported . The IR and UV−vis spectra of benzocyclopropenone, prepared in an argon matrix at 12 K, were also claimed on the basis that the experimental data were in agreement with the calculated harmonic vibrational frequencies reported by Schaefer's group using the HF/DZ+P method .…”

Section: Introductionsupporting

confidence: 69%

Ab Initio Studies of Benzocyclopropenone, Benzocyclopropenone-Containing [2.2]paracyclophane, Its Benzyne Derivative, and the Bridged Benzobarrelene Formed by Intramolecular [4 + 2]Cycloaddition

Pittman

Sæbø

2000

J. Org. Chem.

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Ab initio calculations were carried out on cyclopropenone, 1, benzocyclopropenone, 2, the benzocyclopropenone-containing [2.2]paracyclophane derivative tetracyclo[8.3.2.(4,7)O(11,13)]heptadeca-1(13),4,6,10,14,16-hexaen-12-one, 3, its decarbonylation product tricyclo[8.2.2.2(4,7)]hexadeca-1(12), 4,6,10,13-pentaen-15-yne, 5, a benzyne intermediate, and the bridged benzobarrelene derivative, pentacyclo[5.5.2.2.(1,4)O(4,14)O(10,13)]hexadeca-2,7,9,13,15-pentaene, 6. These calculations suggest that benzocyclopropenone-containing [2.2]paracyclophane, 3, and highly strained bridged benzobarrelene, 6, could exist as stable species. Both aryl rings of the benzocyclopropenone derivative 3 are predicted to be distorted from planarity. This distortion relieves some angle strain present in planar benzocyclopropenone due to the presence of the annulated three-membered ring. Calculations on benzobarrelene, 8, and [2.2]paracyclophane, 4, were performed for comparison to gain a better understanding of the strain borne in bridged benzobarrelene 6. The activation barrier for the intramolecular [4 + 2] cycloaddition of 5 to give 6 was estimated at 18.8 kcal/mol while that for the corresponding [2 + 2] cycloaddition, giving the less stable 9, was 54.5 kcal/mol. The [2 + 2] cycloaddition's transition state was twisted in a manner reminiscent of the conservation of orbital symmetry prediction for an unstrained system.

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Section: Introductionsupporting

confidence: 69%

Ab Initio Studies of Benzocyclopropenone, Benzocyclopropenone-Containing [2.2]paracyclophane, Its Benzyne Derivative, and the Bridged Benzobarrelene Formed by Intramolecular [4 + 2]Cycloaddition

Pittman

Sæbø

2000

J. Org. Chem.

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“…The latter had previously been studied in solution below Ϫ78°C. [33] However, protected from hydrolysis by the surrounding host shell, it proved to be stable at room temperature, allowing its X-ray crystal structure analysis. [34] In the solid state, the C 2 axis of the guest 19 is parallel to the long polar axis of 2, as shown schematically in Figure 3.…”

Section: Benzocyclopropenone and O-benzynementioning

confidence: 99%

“…The formation of identical carbene dimerization products Ϫ heptafulvalene, cis-and trans-stilbenes (31 and 32) Ϫ upon thermolysis of either phenyldiazomethane(33) or the sodium salt 34 of tropone tosylhydrazone demonstrated the reversibility of the phenylcarbene rearrangement [45]. This ledBaron et al to predict the formation of styrene and benzocyclobutene as rearrangement products of the three…”

mentioning

confidence: 99%

Inner-Phase Stabilization of Reactive Intermediates

Warmuth

2001

Eur. J. Org. Chem.

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Molecular container compounds are spherical, hollow molecules with inner cavities (inner phases) that are large enough to accommodate a single guest molecule. These inner phases are superb environments for the stabilization and spectroscopic investigation of important reactive intermediates. The surrounding host protects the incarcerated reactive intermediate from dimerization or from a reaction with bulk‐phase reactants that are too large to enter the inner phase by passing through a portal in the host shell.

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“…Benzocyclopropenone 72 had previously been studied in solution below − 78 ° C, where it rapidly hydrolyzed in the presence of moisture. 57 However, protected inside the hemicarcerand, it was stable at room temperature in water -saturated CDCl 3 . The proton chemical shifts of incarcerated 72 suggest co -alignment of its C2 axis with the C4 axis of 4 (Figure 9.21 ) such that the reactive C = O resides in the shielded region of the inner phase, which explains the high stability of the incarcerated guest.…”

Section: O -Benzynementioning

confidence: 99%

Reactions Inside Carcerands

Warmuth

2010

Molecular Encapsulation

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1H and 13C NMR spectra of benzocyclopropenone in liquid solutions at 193 K

Cited by 13 publications

References 4 publications

Ab Initio Studies of Benzocyclopropenone, Benzocyclopropenone-Containing [2.2]paracyclophane, Its Benzyne Derivative, and the Bridged Benzobarrelene Formed by Intramolecular [4 + 2]Cycloaddition

Ab Initio Studies of Benzocyclopropenone, Benzocyclopropenone-Containing [2.2]paracyclophane, Its Benzyne Derivative, and the Bridged Benzobarrelene Formed by Intramolecular [4 + 2]Cycloaddition

Inner-Phase Stabilization of Reactive Intermediates

Reactions Inside Carcerands

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