54211-14-2Relevant articles and documents
Nickel-catalyzed ring-opening hydroacylation of methylenecyclopropanes: Synthesis of γ,δ-unsaturated ketones from aldehydes
Taniguchi, Hiroki,Ohmura, Toshimichi,Suginome, Michinori
, p. 11298 - 11299 (2011/02/28)
(Chemical Equation Presented) A nickel-catalyzed intermolecular hydroacylation of methylenecyclopropanes (MCPs) has been developed. The reaction proceeds with stereospecific cleavage of the proximal C-C bond of the cyclopropane ring to give γ,δ-unsaturate
1992 Merck-Frosst Award Lecture. Orbital symmetry and the photochemistry of cyclobutene
Leigh, William J.
, p. 147 - 155 (2007/10/02)
Direct photolysis of alkyl-substituted cyclobutene derivatives in solution with monochromatic far-UV light sources results in competing ring opening to the corresponding substituted 1,3-butadiene derivatives and fragmentation to the corresponding alkene and alkyne via formal cycloreversion.The excited states leading to the two types of products have been identified.Cycloreversion occurs stereospecifically and arises as a result of excitation of the ?,R(3s) Rydberg state, which is of comparable energy to the ?,?* state in alkylcyclobutenes.In spite of its stereospecificity, the reaction is nonconcerted; evidence is presented to suggest that it occurs by a mechanism involving migration (ring contraction) to yield a cyclopropylcarbene intermediate, which then fragments to yield the alkyne and alkene.The stereochemistry at C3 and C4 in the starting cyclobutene is retained in the alkene produced in the reaction.Ring opening proceeds nonstereoselectively (from the ?,?* singlet state) in well over a dozen systems that have been investigated, and possible mechanisms to account for this are discussed.It is proposed that orbital symmetry plays a role in the reaction, but only in the early stages of ring opening.Bicyclic cyclobutene derivatives in which the cyclobutene double bond is located across the bridge undergo ring opening with a high degree of disrotatory stereoselectivity.Possible reasons for this unusual behaviour are discussed in light of recent ab initio theoretical results.
CARBOPALLADATION DES ALKYLIDENECYCLOPROPANES-I; CAPTURE INTERMOLECULAIRE DE L'ORGANOPALLADIQUE INTERMEDIAIRE
Fournet, Guy,Balme, Genevieve,Gore, Jacques
, p. 5809 - 5820 (2007/10/02)
The reaction of methylenecyclopropane and 1-cyclopropylidene pentane with iodobenzene or 2-bromopropene and a delocalized anion (issued from malonate or from a β-sulfonyl ester) in the presence of catalytic amounts of a palladium (0) complex leads to conj
Cyclobutene Photochemistry. Nonstereospecific Photochemical Ring Opening of Simple Cyclobutenes
Clark, K. Brady,Leigh, William J.
, p. 6086 - 6092 (2007/10/02)
The photochemistry of bicyclohept-6-ene, bicyclooct-7-ene, and cis- and trans-3,4-dimetylcyclobutene has been investigated in hydrocarbon solution with monochromatic far-ultraviolet (185 and 193 nm) light sources.All of these simple cyclobutene derivatives undergo ring opening to yield the isomeric 1,3-dienes, and the latter three open nonstereospecifically to yield mixtures of the possible geometric isomers.The isomeric 3,4-dimethylcyclobutenes yield different mixtures of the three 2,4-hexadiene isomers, and in each case the mixtures are weighed in favor of the orbital symmetry forbidden isomer(s).Attempts have been made to analyze the relative isomeric diene yields from ring opening of bicyclooctene and the isomeric 3,4-dimethylcyclobutenes within the context of the purely disrotatory, adiabatic ring-opening mechanism that recent ab initio calculations suggest should be possible.While the results for the former compound are consistant with this mechanism, analysis of the relative yields of the isomeric 2,4-hexadienes from photolysis of the latter two compounds indicates that photochemical ring opening by the formally forbidden, conrotatory pathway may compete to some extent with disrotatory ring opening.
SYNTHESIS AND THERMAL TRANSFORMATIONS OF BICYCLOALKENES CONTAINING A METHYLENECYCLOPROPANE FRAGMENT
Mil'vitskaya, E. M.,Pekhk, T. I.,Pereslegina, N. S.,Tarakanova, A. V.,Ivanov, A. V.
, p. 1573 - 1583 (2007/10/02)
The previously undescribed 8-methylenebicyclooct-2-ene (II) and 9-methylenebicyclonon-4-ene (IV) were synthesized by the dehydrohalogenation of 8-methyl-8-chlorobicyclooct-2-ene and 9-methyl-9-chlorobicyclonon-4-ene.It was established that the hydrocarbon (II) is thermally labile, whereas the hydrocarbon (IV) does not change right up to 300 deg C.The thermal transformations of the hydrocarbon (II) and its isomeric bicyclonona-1,6-diene (III) at 100 - 180 deg C were investigated.At 100 deg C a pseudoequilibrium is established between these hydrocarbons.The final and only products from the transformations of both hydrocarbons at 180 deg C are the previously unknown anti-Bredt hydrocarbon bicyclonona-2,7-diene (XXVIIIb) and 3-methylene-1,4-cyclooctadiene (XXV), formed in a ratio of 1 : 2.5.
Syntheses and equilibria of fused bicyclic methylenecyclopropanes
Kende, Andrew S.,Riecke, Edgar E.
, p. 383 - 384 (2007/10/10)
Isomeric bicyclic methylenecyclopropanes, obtained from carbenoid ring contraction of bicyclic cyclobutanones, exhibit extraordinarily clean thermal equilibria which is entropy-controlled near the boundaries of Bredt's rule.
