1165952-91-9Relevant academic research and scientific papers
Cyclization of Ethyne and Propyne over Lanthanide Catalysts Deposited from Eu or Yb Metal Solutions in Liquid Ammonia
Imamura, Hayao,Suda, Eisaku,Konishi, Tomohiro,Sakata, Yoshihisa,Tsuchiya, Susumu
, p. 215 - 216 (1995)
Europium and ytterbium catalysts separated on active carbon from a solution of lanthanide metals dissolved in liquid ammonia were found to be effective for oligomerization of alkynes.Selective cyclic dimerization and trimerization of propyne and ethyne to cyclohexadiene and benzene occurred during the oligomerization, respectively, in which the active catalysts were characterized as lanthanide imides induced by the thermal treatment.
THE THERMAL REARRANGEMENT OF CIS,CIS-1-FLUORO-2-METHYL-3-VINYLCYLOPROPANE. THE KINETIC EFFECT OF A SINGLE FLUORINE SUBSTITUENT
Elsheimer, Seth,Dolbier, William R.
, p. 119 - 128 (1988)
It was demonstrated through a kinetic study of the thermal rearrangement of cis,cis-1-fluoro-2-methyl-3-vinylcyclopropane to cis-3-fluoro-1,4-hexadiene that a single fluorine substituent lowers that activation barrier for rearrangement by about 2 kcal/mole as compared to 6.4 kcal/mole for geminal difluoro substitution.
Regioselective Catalytic Transfer Hydrogenation of Dimethyl Bicyclohepta-2,5-diene-2,3-dicarboxylate, Dimethyl Bicyclohept-2-ene-2,3-dicarboxylate, and Related Compounds over Palladium on Carbon
Tabor, Derrick C.,White, Franklin H.,Collier, L. Warren,Evans, Slayton A.
, p. 1638 - 1643 (1983)
The catalytic transfer hydrogenation (CTH) of dimethyl bicyclohepta-2,5-diene-2,3-dicarboxylate (3) on palladium on carbon is highly regioselective, giving predominant reduction at the least-substituted olefinic site.The CTH of dimethyl bicyclohept-2-ene-2,3-dicarboxylate also occurs with exclusive suprafacial exo addition of hydrogen to afford the endo isomer.An increase in the relative concentration of palladium on carbon (ca. 40-45 wt/wt percent based on the acceptor) accelerates the rate of CTH while the substituted cyclohexenes undergo CTH faster than cyclohexene with dimethyl bicyclohept-2-ene-2,3-dicarboxylate.
Tellurolate-Induced 1,4-Elimination of 1,4-Dibromo-2-Enes. Syntheses of 1,3-Dienes
Engman, Lars,Bystroem, Styrbjoern E.
, p. 3170 - 3174 (1985)
Sodium 2-thienyltellurolate, generated in catalytic amounts from sodium borohydride and bis(2-thienyl) ditelluride, was found to efficiently debrominate 1,4-dibromo-2-olefins to 1,3-dienes under very mild reaction conditions.The required 1,4-dibromo-2-olefins were usually synthesized by allylic α,α'-bromination of olefins.Terminal olefins yielded, via allylic rearrangement, a mixture of 1,4-dibromo-2-olefins and 1,2-dibromo-3-olefins.Both these isomers were converted to 1,3-dienes (E/Z ca. 9/1) by the tellurolate reagent.The syntetic utility of the tellurolate-induced debromination reaction was demonstrated in a two-step synthesis of the main component of the red bollworm moth sex pheromone.
Thermal chemistry of bicyclo[4.2.0]oct-2-enes
Powers, David C.,Leber, Phyllis A.,Gallagher, Sarah S.,Higgs, Andrew T.,McCullough, Lynne A.,Baldwin, John E.
, p. 187 - 194 (2007)
At 300 °C, bicyclo[4.2.0]oct-2-ene (1) isomerizes to bicyclo[2.2.2]oct-2-ene (2) via a formal [1,3] sigmatropic carbon migration. Deuterium labels at C7 and C8 were employed to probe for two-centered stereomutation resulting from C1-C6 cleavage and for one-centered Stereomutation resulting from C1-C8 cleavage, respectively. In addition, deuterium labeling allowed for the elucidation of the stereochemical preference of the [1,3] migration of 1 to 2. The two possible [1,3] carbon shift outcomes reflect a slight preference for migration with inversion rather than retention of stereochemistry; the si/sr product ratio is ～1.4. One-centered stereomutation is the dominant process in the thermal manifold of 1, with lesser amounts of fragmentation and [1,3] carbon migration processes being observed. All of these observations are consistent with a long-lived, conformationally promiscuous diradical intermediate.
An Experimental and Theoretical Evaluation of the Intramolecular Reactions of Cyclohexyne
Tseng, John,McKee, Michael L.,Shevlin, Philip B.
, p. 5474 - 5477 (1987)
The intramolecular reactions of cyclohexyne (1a) have been explored theoretically by using ab initio calculations at the Mp2/6-31G* level and experimentally by examining the ring expansion of cyclopentylidenecarbene (2a) at elevated temperatures.The calculations indicate that 1a is more stable than 2a by 19.0 kcal/mol and that the barrier for 1a -> 2a is 26.4 kcal/mol.Carbene 2a can rearrange to bicyclohex-5-ene and thence to cyclohexadiene with a barrier of 38.9 kcal/mol.A higher energy reaction of 1a is cleavage to ethylene and butatriene in a retro-Diels-Alder reaction, which is calculated to have a barrier of 46.8 kcal/mol.This retro-Diels-Alder reaction is observed experimentally when 2a is generated by the pyrolysis of the cyclopentylidene adduct of Meldrum's acid.
Central and Lateral Bicyclo[1.1.0]butane Bond Cleavage with Subsequent Wagner-Meerwein Rearrangements or Carbene Formation in the 185-nm Photolysis of Tricyclo[3.1.0.02,6]hexane, Tricyclo[4.1.0.02,7]heptane, and Tricyclo[5.1.0.02,8]octane
Adam, Waldemar,Alt, Christine,Braun, Max,Denninger, Uwe,Zang, Gerald
, p. 4563 - 4571 (1991)
The 185-nm photochemistry of tricyclop[3.1.0.02,6]hexane, tricyclo[4.1.0.02,7] heptane, [1,7-d2]tricyclo[4.1.0.02,7]heptane, tricyclo[5.1.0.02,8]octane, and [1-d]tricyclo[5.1.0.02,8]octane was investigated. Tricyclo[5.1.0.02,8]octane yields bicyclo[4.2.0]oct-7-ene, tricyclo[4.1.0.02,7]heptane yields 85% bicyclo[3.2.0]hept-6-ene and 15% 3-methylenecyclohexene, and tricyclo[3.1.0.02,6]hexane yields 39% 3-methylenecyclopentene, 15% 1,3-cyclohexadiene, 26% trans-1,3,5-hexatriene, and 20% cis-1,3,5-hexatriene. From the deuterium-labeling studies, it is concluded that, in the case of the tricyclooctane, the central bicyclobutane bonds cleave in the primary step to give radical cationic or zwitterionic species that undergo a Wagner-Meerwein rearrangement. Also, in the case of tricycloheptane, this is the dominating pathway but lateral C-C bond cleavage with subsequent carbene and product formation takes place to the extent of ca. 15%. For tricyclohexane, this pathway becomes the major route. Our photomechanistic observations are in good agreement with earlier theoretical investigations on the relative energetic ordering of the bicyclobutane HOMOs, in that the product composition reflects this.
Thermal reactions of 7-d- and 8-d-bicyclo[4.2.0]oct-2-enes
Baldwin, John E.,Leber, Phyllis A.,Powers, David C.
, p. 10020 - 10021 (2006)
The gas phase thermal reactions exhibited by bicyclo[4.2.0]oct-2-ene and 7-d and 8-d analogues at 300 °C have been followed kinetically through GC and 2H NMR spectroscopic analyses. In contrast to the pattern of transformations exhibited by bicyclo[3.2.0]hept-2-ene and deuterium-labeled analogues, no reactions initiated by C1-C6 bond cleavage are seen, epimerization at C8 is much faster than [1,3] shifts leading to bicyclo[2.2.2]oct-2-ene, and the ratio of rate constants for [1,3] carbon migration with inversion versus migration with retention is ～1.4. Homolysis of C1-C8 to give a conformationally flexible diradical intermediate having a relatively long lifetime and multiple options for further reaction (re-formation of C1-C8 with or without net epimerization, fragmentation to 1,3-cyclohexadiene and ethylene, migration to the original C3 with inversion or retention) accords well with the observations. Clearly, orbital symmetry control does not govern stereochemistry for the [1,3] sigmatropic carbon shifts. Copyright
NMR spectroscopic and computational investigations of RuHCl(CO)(PPh 3)3 catalyzed isomerization of 1,4-cyclohexadiene
Mao, James X.,Mathers, Robert T.,Damodaran, Krishnan
, p. 15 - 19 (2013)
Ruthenium catalysts with bulky ligands are particularly effective for diene isomerization reactions. Thermodynamics and the mechanism of RuHCl(CO)(PPh3)3 catalyzed 1,4-cyclohexadiene isomerization was probed experimentally through NMR spectroscopy and mod
Kinetics and mechanism of monomolecular heterolysis of commercial organohalogen compounds: XL. Nature of salt effects in dehydrobromination of 3-bromocyclohexene in γ-butyrolactone. Role of solvation effects of dipolar aprotic solvents
Ponomarev,Stambirskii,Dvorko
, p. 883 - 890 (2005)
The influence of neutral salts on the rate of heterolysis of 3-bromocyclohexene at 31°C in γ-butyrolactone was studied by the verdazyl method; ν = k[C6H9Br], E1 mechanism. Additions of lithium picrate do not affect the reaction rate;
