10563-01-6Relevant articles and documents
Photochemistry of cyclopentadiene isolated in low-temperature argon matrices
Miyazaki, Jun,Yamada, Yasuhiro
, p. 145 - 153 (2004)
The photochemistry of cyclopentadiene isolated in low-temperature argon matrices was studied by means of IR and UV/VIS spectroscopy. Bicyclo[2.1.0]pent-2-ene was formed by the irradiation of matrix-isolated cyclopentadiene using a super-high-pressure mercury lamp. When the matrix-isolated cyclopentadiene was irradiated with shorter wavelength using a low-pressure mercury lamp, further reactions of bicyclo[2.1.0]pent-2-ene were found to produce allylacetylene and vinylallene. While the photochemistry of cyclopentadiene to form bicyclo[2.1.0]pent-2-ene is known in a solution system, the production of allylacetylene and vinylallene in a matrix-isolated system has never been previously reported. The assignments of the species and the determination of the reaction mechanisms were performed using molecular orbital calculations.
TRICYCLO1,3>PENTANE
Wiberg, Kenneth B.,McClusky, John V.
, p. 5411 - 5414 (2007/10/02)
The reaction of 1,1-dibromo-2,3-bis(chloromethyl)cyclopropane with methyllithium leads initially to ring closure to 1-bromo-2-chloromethylbicyclobutane.Further reaction leads to an unstable compound which reacts with phenylthiol to give 2-vinyl-1-cyclopropyl phenyl sulfide and undergoes thermal rearrangement at -50 deg C to give cyclopentadiene.Strong evidence is presented which suggests that tricyclo1,3>pentane may be the intermediate.
Thermal Rearrangements, XVIII. - Gas Phase Pyrolysis of Cyclopropylacetylene
Hopf, Henning,Wachholz, Gerhard
, p. 1259 - 1262 (2007/10/02)
The gas phase pyrolysis of cyclopropylacetylene (3) has been investigated in a flow system between 600 and 900 deg C.At the lower temperature limit 3 isomerizes to give 1,2,4-pentatriene (9), cis- (10) and trans-3-penten-1-yne (11), as well as 1-penten-4-yne (12), all isomers being formed in roughly equal amounts.At 850 deg C none of these C5H6-hydrocarbons is formed; rather, 1,3-cyclopentadiene (13), benzene (14), toluene (15), indene (16), naphthalene (17), and acenaphthylene (18) are the major constituents of a complex pyrolysate.The mechanisms of formation of the major pyrolysis products are discussed.
THE DIAZO ROUTE TO 2-VINYLCYCLOPROPYLIDENES
Krimse, Wolfgang,Chiem, Pham Van,Henning, Paul-Georg
, p. 1441 - 1452 (2007/10/02)
2-Vinylcyclopropylidene (2), 3-methyl-2-vinylcyclopropylidenes (79,80) and 2-(1-propenyl)cyclopropylidenes (95,97) were generated from the corresponding nitrosoureas in methanol at room temperature.The diazo route is initiated by the formation of 2-vinylcyclopropanediazonium ions (e.g. 43) which do not undergo 1,3-carbon shifts.No cyclopentenyl products were found in weakly basic methanol where the diazonium ions prevail.Ring opening of the diazonium ions gives pentadienyl cations and products derived therefrom.Delocalisation of the pentadienyl cations was demonstrated by the distribution of deuterium and methyl labels.In the presence of strong base, 1-diazo-2-vinylcyclopropanes (e.g. 48) arise by deprotonation of the diazonium ions.Rearrangement of 48 was excluded by independent generation of the potential product, 4-diazocyclopentene (103).Substantial quantities of 3-methoxycyclopentene (108) were obtained from 103, but not from 48.The 2-vinylcyclopropylidenes 2, 79 and 95, arising by loss of nitrogen from the corresponding diazo compounds, undergo allene formation and Skatteboel rearrangement competitively.Cis-oriented methyl groups at either C-2 (81) or C-2' (97) prevent the Skattebol rearrangement.The cyclopentenylidenes 3 and 83 yield 4-methoxycyclopentes (52,86) in excess over cyclopentadiens (4,84).In the presence of methyl vinyl ether, cycloaddition of 3 and electrophilic addition of 3-cyclopentenyl cation (51) occured in a 1:14 ratio.Stereospecific formation of 52 indicates protonation of a 'foiled carbene' (3a) to give a bishomocyclopropenyl ion (51a).Our studies confirm that the various routes to 2-vinylcyclopropylidenes converge at the carbene stage.
