6553-48-6Relevant articles and documents
Evidence for pericyclic and stepwise processes in the cyclodimerization of chloroprene and 1,3-butadiene from pressure dependence and stereochemistry. Experimental and theoretical volumes of activation and reaction
Kl?rner, Frank-Gerrit,Krawczyk, Bernd,Ruster, Volker,Deiters, Ulrich K.
, p. 7646 - 7657 (2007/10/02)
From the pressure dependence of cyclodimerization of chloroprene, it has been concluded that volumes of activation may be useful for the distinction between competing concerted and stepwise cycloadditions. Accordingly, one of the [4 + 2] cyclodimers, 1,4-
Alkynes and Cumulenes, XVII, Photoaddition of Vinylacetylene to other Unsaturated Hydrocarbons
Siegel, Herbert,Eisenhuth, Ludwig,Hopf, Henning
, p. 597 - 612 (2007/10/02)
On irradiation in the presence of triplet sensitizers, vinylacetylene (1) may be added with its double bond to olefins , dienes , allenes , and diynes .The resulting multifunctionalized cyclobutane derivatives are characterized by spectroscopic and chemical methods.Since the ethinyl group of these codimers may be hydrated to the acetyl function, 1 represents a photochemical equivalent of methyl vinyl ketone which itself does not undergo the described photoadditions.When benzene (56) is employed as addition partner the primary product of the codimerisation, 54, isomerizes to vinylcyclooctatetraene (55).
Small Rings. Part 32. The Gas Phase Kinetics, Mechanism, and Energy Hypersurface for the Thermolyses of syn- and anti-Tricyclo2,5>-octane
Walsh, Robin,Martin, Hans-Dieter,Kunze, Michael,Oftring, Alfred,Beckhaus, Hans-Dieter
, p. 1076 - 1083 (2007/10/02)
The title reactions have been studied at low pressure (1-10 Torr) and in the temperature ranges 390-419 2,5/octane(syn-TCO)> and 412-445 K (anti-TCO).The major products from both compounds were cis,cis and cis,trans-cyclo-o
Photochemistry of Alkenes. 6. Direct Irradiation of 1,5-Hexadienes: and Sigmatropic Allyl Shifts
Manning, T. D. R.,Kropp, Paul J.
, p. 889 - 897 (2007/10/02)
The photochemical behavior of a series of alkyl-substituted 1,5-hexadienes has been studied.Competing allylcyclopropane formation and rearrangement to an isomeric 1,5-hexadiene via competing and sigmatropic allyl shifts, respectively, were observed.In one case a product (30 from 27) and in another a product (35 from 31) was obtained, but only in low yield.Extensive cis trans isomerization competed with the allyl shifts, and, in addition, other products were obtained which are characteristic of the photochemical behavior of isolated double bonds.At low conversion diene 10t underwent stereoselective rearrangement to 8t and 11t, whereas the cis isomer 10c afforded mixtures of the cis and trans isomers of 8 and 11.Attempts to induce the allyl migrations by sensitization with p-xylene or by irradiation at 254 nm afforded only cis trans isomerization.It is concluded that the allyl migrations occur via an excited state involving interaction between the double bonds and requiring a conformation in which the central C3-C4 bond is in a plane orthogonal to both double bonds, as proposed previously.In contrast with the acyclic dienes, 1,5-cyclooctadiene (50) afforded products 51-53 from competing , , and allyl shifts, respectively.The divergent behavior in this case apparently arises because appropriate interaction between the two double bonds can occur only in the boat conformation.
Diene Oligomerization. XV. Palladiumcomplexcatalyzed Telomerization of Butadiene with Amines and Dimerization in the Presence of Ketoximes
Beger, J.,Meier, F.
, p. 69 - 80 (2007/10/02)
Butadiene reacts with primary or secondary amines and with the homogeneous catalytic system bis-acetylacetonatopalladium-(II)/triphenylphosphine to form 1-amino-octa-2,7-dienes.The rate and the selectivity of the reaction increase in presence of cocatalysts as triarylphosphates instead of triphenylphosphine and if the reaction proceeds in a protic media - in alcohols, water or lower carboxylic acids.A number of 1-aminoocta-2,7-dienes were prepared.If oximes act as organic nitrogen compounds, only n-octa-1,3,7-triene is selectively formed.Schiff' bases aldolisate under the conditions of the reaction.
The C8H12-Energy Hypersurface Thermolysis of syn- and anti-Tricyclo2,5>octane. Experimental and Theoretical Studies
Martin, Hans-Dieter,Eisenmann, Erwin,Kunze, Michael,Bonacic-Koutecky, Vlasta
, p. 1153 - 1179 (2007/10/02)
The thermal behaviour of syn- and anti-tricyclo2,5>octanes 9 and 10 in the gas phase as well as in solution is investigated.Two main products are formed in parallel reactions: cis,cis-1,5-cyclooctadiene (11) and cis,trans-1,5-cyclooctadiene (15), the latter being partly isomerized to 11 under the reaction conditions.Minor products are cis-1,2-divinylcyclobutane (6), trans-1,2-divinylcyclobutane (16) and 4-vinyl-1-cyclohexene (17).Thermolysis of cis-1,2-divinylcyclobutane leads to small amounts of cis,trans-cyclooctadiene, presumably via a four-centre transition state.The tricyclics most likely prefer a stepwise isomerization.The decisive product-controlling factor seems to be the conformational mobility of intermediate diradicals.By comparison with the boat-Cope reaction of divinylcyclobutane the pericyclic six-centre transition state of this rearrangements is shown to lie energetically about 19 kcal/mol below the transition states in the thermolysis of 9 and 10.The azo compound 12 on heating fragments predominantly in a concerted manner in contrast to the photolysis.Theoretical methods are applied to unveil structure and bonding in the supposed intermediate diradicals.
