1,2‐Didehydrobenzol: ein gespanntes Alkin oder ein Cumulen? — NMR‐spektroskopische Charakterisierung in einem molekularen Container

Warmuth, Ralf

doi:10.1002/ange.19971091234

Cited by 83 publications

(18 citation statements)

References 35 publications

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“…Die thermochemischen Eigenschaften der Singulett‐ und Triplett‐Zustände wurden bestimmt,8, 9 und auch IR‐spektroskopische Untersuchungen an den ortho‐ 10 und meta ‐Isomeren11 wurden durchgeführt. Die Struktur von ortho ‐Benz‐in wurde NMR‐spektroskopisch analysiert 12. Somit steht nur noch für das para ‐Isomer 1 ‐ p eine genaue spektroskopische Charakterisierung aus, obwohl hierzu Daten in begrenztem Umfang vorliegen 9…”

Section: Methodsunclassified

Zum systematischen Abbau von Benzol

Wenthold

2005

Angewandte Chemie

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Section: Methodsunclassified

Zum systematischen Abbau von Benzol

Wenthold

2005

Angewandte Chemie

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“…Sodium hydride (85 % in oil, 0.56 g, 20.0 mmol) was added to tricarbonyl(η 6 -2,5-dimethoxyphenol)chromium(0) (12,4.01 g, 13.9 mmol) in CH 2 Cl 2 (50 mL). After the mixture had been cooled to -78°C, triflic anhydride (2.4 mL, 14.2 mmol) was added to the stirred mixture.…”

Section: Tricarbonyl[η 6 -(25-dimethoxyphenyl Triflate)]chromium(0) mentioning

confidence: 99%

“…Arynes [1,2] (dehydrobenzenes) are valuable intermediates combining important aspects of theory, [3] spectroscopy, [4] and applications for the synthesis of natural [5,6] and unnatural products. [7][8][9][10] Methods for the generation of 1,2-dehydrobenzene involve elimination from aryl anions, aryl cations, aryl radicals, and zwitterions, as well as fragmentation reactions.…”

Section: Introductionmentioning

confidence: 99%

Attempts Directed towards the Synthesis of Intermediate (Aryne)chromium Complexes from Aryl Triflates and from (Haloarene)chromium Complexes

Werner

Butenschön

2012

Eur J Org Chem

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The generation of (η6‐aryne)chromium complexes as reactive intermediates was investigated in two ways. Although earlier attempts directed towards triflate eliminations from a variety of tricarbonyl(phenyl triflate)chromium complexes had failed, more electron‐rich phenyl triflate complexes were considered. This was accomplished either by substitution with two methoxy groups in the arene ligand or by replacement of one of the three carbonyl ligands of the tricarbonylchromium complex with triphenylphosphane. However, the attempted elimination still did not take place; in spite of the increased electron densities in the aromatic ligands, anionic thia‐Fries rearrangements were observed in high yields at –78 °C. As an alternative, elimination of lithium fluoride was tested. Tricarbonyl(2‐lithiofluorobenzene)chromium(0) was generated by tin/lithium exchange. After hydrolytic workup, tricarbonyl(fluorobenzene)chromium was obtained as the main product, indicating that the lithiation step had been successful. A dimeric side product provided evidence for the intermediacy of (benzyne)tricarbonylchromium.

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“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) active intermediates have been generated and stabilized by preventing their dimerization or the reaction with bulkphase reactants that are too large to enter the inner phase. [6][7][8][9][10][11][12][13][14][15][16][17] Encapsulation has also been applied to investigate fundamental aspects of electron and energy transfer processes, [18][19][20][21][22] to change and control the rate and regiochemistry of bimolecular reactions, [23][24][25][26][27][28][29][30][31][32][33] to amplify reactions, [34] and to alter the position of chemical equilibria. [35] Recently, Rebek and co-workers and Fujita and coworkers showed that Diels-Alder reactions and photochemical [2+2] additions are strongly accelerated in the presence of a self-assembled capsule or coordination cage.…”

Section: Introductionmentioning

confidence: 99%

Inner‐Phase Reaction Dynamics: The Influence of Hemicarcerand Polarizability and Shape on the Potential Energy Surface of an Inner‐Phase Reaction

et al. 2005

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The thermal decomposition of six phenyldiazirine (2) hemicarceplexes and the spectroscopic properties of these hemicarceplexes, as well as those of one spiro[cyclobutabenzene-1(2H),3Ј-diazirine] (1) and one p-tolyldiazirine (3) hemicarceplex, have been investigated in order to determine the effect of a hemicarcerand on the potential energy surface of an inner-phase reaction. These hemicarceplexes have pentyl or phenethyl feet groups, three tetramethylene linkers and differ in the nature of one linker group X as follows: 1: X = (CH 2 ) 5 ; 2: X = (CH 2 ) n (n = 2, 3, 4), (S,S)-CH 2 CH[OC(CH 3 ) O]CHCH 2 and ortho-CH 2 C 6 H 4 CH 2 ; 3: X = (CH 2 ) 4 . The effect of the linker group X on the structure of the phenyldiazirine hemicarceplexes was analyzed by MM2 force field calculations and leads to a change in the bending of the inner phase, which increases in the order (S,S)-CH 2 CH[OC(CH 3 ) O]CHCH 2 Ͼ (CH 2 ) 4 Ͼ (CH 2 ) 3 Ͼ (CH 2 ) 2 Ͼ ortho-CH 2 C 6 H 4 CH 2 and to a shortening of the center-to-center distance between the two cavitands of the host, which decreases in the order (S,S)-CH 2 CH[OC(CH 3 )O]CHCH 2 Ͻ (CH 2 ) 4 Ͻ (CH 2 ) 3 Ͻ (CH 2 ) 2 Ͻ ortho-CH 2 C 6 H 4 CH 2 . All hemicarceplexes show large red shifts of the diazirine n-π*-transition in their UV/Vis absorption spectra. From the red shifts and from plots of the n-π*-excitation energy of the free diazirines against the solvent polarizability P, the inner-phase po-

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1,2‐Didehydrobenzol: ein gespanntes Alkin oder ein Cumulen? — NMR‐spektroskopische Charakterisierung in einem molekularen Container

Cited by 83 publications

References 35 publications

Zum systematischen Abbau von Benzol

Zum systematischen Abbau von Benzol

Attempts Directed towards the Synthesis of Intermediate (Aryne)chromium Complexes from Aryl Triflates and from (Haloarene)chromium Complexes

Inner‐Phase Reaction Dynamics: The Influence of Hemicarcerand Polarizability and Shape on the Potential Energy Surface of an Inner‐Phase Reaction

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