Substitutionsprodukte des Cyclopentadiens, 5. Mitt.: 1- und 2-tert.-Butylcyclopentadien

Riemschneider, R.; Reisch, A.; Horak, H.

doi:10.1007/bf00929551

Cited by 23 publications

(10 citation statements)

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“…o -Xylene used in ESR experiments was treated with concentrated sulfuric acid and distilled from sodium/benzophenone ketyl under an argon atmosphere. t -BuC 5 H 5 , C 5 H 5 Me 2 SiSiMe 2 Cl, (Me 2 SiSiMe 2 )[(η 5 -C 5 H 4 )Fe(CO)] 2 (μ-CO) 2 ( 1 ), and [Me 2 Si(η 5 -C 5 H 4 )Fe(CO) 2 ] 2 ( 2 ) 5 were prepared according to literature methods. Proton ( 1 H NMR) spectra were obtained on a Bruker AC-P200 or JEOL FX-90Q spectrometer.…”

Section: Methodsmentioning

confidence: 99%

Novel Rearrangement Reactions. 1. Molecular Rearrangement via Metathesis between Intramolecular Si−Si and Fe−Fe Bonds

et al. 1997

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Thermal treatment of t-BuC5H4Me2SiSiMe2C5H4-t-Bu with Fe(CO)5 in xylene gave the diiron complex (Me2SiSiMe2)[(η5-t-BuC5H3)Fe(CO)]2(μ-CO)2 (3), existing as a mixture of cis and trans isomers (3c and 3t) which were separated by preparative TLC. When the two isomers were heated respectively in xylene, the cis substrate (3c) rearranged to the trans product [Me2Si(η5-t-BuC5H3)Fe(CO)2]2 (4t), while the trans substrate (3t) afforded the cis product [Me2Si(η5-t-BuC5H3)Fe(CO)2]2 (4c). This indicates that the rearrangement reaction is stereospecific. Complexes [(η5:η5-C5H4Me2SiSiMe2C5R3R‘)Fe(CO)]2(μ-CO)2 (R = H, R‘ = t-Bu, 5; R = R‘ = Me, 6), containing different cyclopentadienyl groups, were prepared similarly. Their respective rearrangement reactions only yielded the corresponding unsymmetrical products [(Me2Si)(η5-C5H4)Fe(CO)2][(Me2Si)(η5-C5R3R‘)Fe(CO)2] (R = H, R‘ = t-Bu, 7; R = R‘ = Me, 8); no symmetrical disproportionation products were detected. This indicates that the reaction proceeds via an intramolecular rather than intermolecular pathway. The conclusion is further confirmed by the fact that no crossover product was formed in subsequent rearrangement between two different substrates. Probing the reaction by ESR spectroscopy shows that the reaction proceeds via an intermediate containing iron-centered radicals. On the basis of these experimental facts, an alternative mechanism for the rearrangement reaction is proposed. Molecular structures of 3c, 3t, 4t, and 4c were determined by X-ray diffraction.

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Section: Methodsmentioning

confidence: 99%

Novel Rearrangement Reactions. 1. Molecular Rearrangement via Metathesis between Intramolecular Si−Si and Fe−Fe Bonds

et al. 1997

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“…Elemental analyses were performed by a Perkin-Elmer 240C spectrometer. 1,2-dichlorotetramethyldigermane 10 and t-BuC 5 -H 5 11 was prepared according to literature methods.…”

Section: Methodsmentioning

confidence: 99%

Novel thermal rearrangement reactions: rearrangement stereospecificity of complex [Fe2(CO)2(μ-CO)2(μ-t-BuC5H3Me2GeGeMe2C5H3Bu-t)]

Xie¹,

Wang²,

Dai³

et al. 1999

J. Chem. Soc., Dalton Trans.

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Thermal treatment of 1,2-bis(3-tert-butylcyclopentadienyl)tetramethyldigermane with [Fe(CO) 5 ] in xylene gave the diiron complex [Fe 2 (CO) 2 (µ-CO) 2 (µ-3-t-BuC 5 H 3 Me 2 GeGeMe 2 C 5 H 3 Bu-t-3)] 1 existing as a mixture of cis and trans isomers (1c and 1t) which were separated by preparative TLC. When the two isomers were heated in xylene the cis substrate (1c) rearranged to a trans product [Fe 2 (CO) 4 (µ-3-t-BuC 5 H 3 GeMe 2 ) 2 ] 2t, while the trans substrate (1t) afforded a cis product 2c. This indicates that the rearrangement reaction is stereospecific, which is consistent with previous results. Molecular structures of 1c, 1t, 2t, and 2c were determined by X-ray diffraction.

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“…The simplest explanation for the change in isomer ratio as a result of irradiation is that 1 is more reactive than 2 in the di-n-methane rearrangement. The fact that only one product (3) was detectable suggests that 2 does not undergo any photorearrangement on direct irradiation, with the possible exception of [1,3]-sigmatropic shifts which would interconvert it with 1. Formation of 3 can be interpreted in terms of the di-n-methane rearrangement (8,16).…”

Section: Photochemistrymentioning

confidence: 99%

“…Product 3, still contaminated with a trace of starting material, was further purified by preparative thin layer chron~atography (silica gel, 50: 50 hexane-cyclohexane). Crystallization from benzene gave 3 as colorless prisms: mp 108-109 "C; molecular ion ( m e ) 308; ir (CCl, and CS2) 3 Table 2.…”

Section: Direct Irradiation Of I Andmentioning

confidence: 99%

“…First, monosubstituted cyclopentadienes are interconverted by thermal [1,5]-sigmatropic hydrogen migration and are obtained as mixtures of isomers (1)(2)(3)(4)(5)(6), any one or all of which could be photolabile. Second, all three possible isomers have the endocyclic di-n-methane system of cyclopentadiene itself but, in the cases of 1-and 2-triphenylmethylcyclopentadienes, P and 2, respectively, there is an additional di-n-methane system consisting of a double bond of the diene moiety and a phenyl group.…”

mentioning

confidence: 99%

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Photoisomerization of 1-triphenylmethylcyclopentadiene. Di-π-methane rearrangement to 5,6,6-triphenylbicyclo[3.1.0]hex-2-ene

Weigl¹,

Warkentin²

1977

Can. J. Chem.

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Triphenylmethylcyclopentadiene exists as a mixture of isomers, the minor and major components of which are shown to be 1-triphenylmethylcyclopentadiene (1) and 2-triphenylmethyl-cyclopentadiene (2), respectively.Direct irradiation of a mixture of 1 and 2 led to formation of 5,6,6,-triphenylbicyclo[3.1.0]hex-2-ene (3) via rearrangement of 1. Acetophenone-sensitized irradiation of the same mixture gave 3 as well as a two component mixture of photodimers of 1 and/or 2. Results are interpreted in terms of the di-π-methane rearrangement mechanism.

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Substitutionsprodukte des Cyclopentadiens, 5. Mitt.: 1- und 2-tert.-Butylcyclopentadien

Cited by 23 publications

References 0 publications

Novel Rearrangement Reactions. 1. Molecular Rearrangement via Metathesis between Intramolecular Si−Si and Fe−Fe Bonds

Novel Rearrangement Reactions. 1. Molecular Rearrangement via Metathesis between Intramolecular Si−Si and Fe−Fe Bonds

Novel thermal rearrangement reactions: rearrangement stereospecificity of complex [Fe2(CO)2(μ-CO)2(μ-t-BuC5H3Me2GeGeMe2C5H3Bu-t)]

Photoisomerization of 1-triphenylmethylcyclopentadiene. Di-π-methane rearrangement to 5,6,6-triphenylbicyclo[3.1.0]hex-2-ene

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