4292-04-0Relevant articles and documents
Alternating copolymerization of ethylene with 7-methylenebicyclo[4.1.0] heptane promoted by the cobalt complex. Highly regulated structure and thermal rearrangement of the obtained copolymer
Takeuchi, Daisuke,Osakada, Kohtaro
, p. 1528 - 1530 (2005)
The Co complex-catalyzed copolymerization of ethylene with 7-methylenebicyclo[4.1.0]-heptane was investigated as an alternative copolymer with a highly regulated structure. The thermally induced ring opening reaction of the copolymer, which gives a new po
A highly selective arene hydrogenation catalyst that operates in ionic liquid
Boxwell, Clive J.,Dyson, Paul J.,Ellis, David J.,Welton, Thomas
, p. 9334 - 9335 (2007/10/03)
The synthesis and structural characterization of [Ru(η6-p-cymene)(η2-TRIPHOS)Cl][PF6] is described. The complex is a highly active, homogeneous arene hydrogenation catalyst that is selective toward the hydrogenation of aromatic rings in preference to alkenes, as demonstrated by the hydrogenation of allylbenzene to allylcyclohexane. The catalyst operates in both dichloromethane and ionic liquids and undergoes no decomposition in the latter solvent. Copyright
BF3·OEt2 promotes fast, mild, clean and regioselective dehydration of tertiary alcohols
Posner,Shulman-Roskes,Oh,Carry,Green,Clark,Dai,Anjeh
, p. 6489 - 6492 (2007/10/02)
BF3·OEt2 in methylene chloride at 25°C for 2 hours or less is shown to be effective for easy conversion of tertiary alcohols into the corresponding thermodynamically most stable alkenes.
Photochemical Dehydrogenation of Alkanes Catalyzed by trans-Carbonylchlorobis(trimethylphosphine)rhodium: Aspects of Selectivity and Mechanism
Maguire, John A.,Boese, William T.,Goldman, Alan S.
, p. 7088 - 7093 (2007/10/02)
The photochemical dehydrogenation of alkanes is catalyzed in solution by trans-Rh(PMe3)2(CO)Cl with high efficiency; quantum yields up to 0.10 and turnover numbers as high as 5000 are achieved with cyclooctane as substrate.The intramolecular regioselectivity of the reaction is investigated with methyl-, ethyl-, and isopropylcyclohexane.In competition experiments, cyclooctane is found to be 17 times as reactive as cyclohexane; under carbon monoxide atmosphere, the selectivity is enhanced to a factor of 130.A kinetic isotope effect, kH/kD=5.3, is found for thedehydrogenation of C6H12/C6D12.Both intra- and intermolecular selectivities are consistent with a pathway involving a reversible C-H oxidative addition followed by a β-hydrogen elimination. trans-Rh(PMe3)2(CO)Cl is demonstrated to be the only significant photoactive species in solution.The dehydrogenation reaction is quenched by carbon monoxide with Stern-Volmer kinetics.On the basis of these results, a mechanism is proposed in which the enrgy needed to drive these thermodynamically unfavorable dehydrogenations is obtained only from Rh-CO bond photolysis.
THIAZOLES IN ORGANIC SYNTHESIS. NOVEL SYNTHESES OF MENTHANES AND EREMOPHILANES
Jacobi, Peter A.,Egbertson, Melissa,Frechette, Roger F.,Miao, Clara K.,Weiss, Kim T.
, p. 3327 - 3338 (2007/10/02)
Acetylenic thiazoles of proper design have been shown to undergo an intramolecular Diels-Alder reaction leading to fused-ring thiophene derivatives.When appropriately substituted, these latter materials can be readily converted to terpenes of the menthane
KINETIC CONTROL IN THE BENZYLIDENATION OF SOME 1-ALKYLCYCLOHEXANE-CIS-1,2-DIOLS
Baggett, Neil,Mosihuzzaman, Mohammed,Webber, John M.
, p. 347 - 356 (2007/10/02)
Acid-catalysed benzylidenation reactions of a series of alkyl substituted derivatives of cyclohexane-cis-1,2-diol have been studied.Preferential formation of the exo-phenyl benzylidene acetal was observed in the initial kinetic phase of the reaction of th
Cyclizations of ω-Allenyl Radicals
Apparu, Marcel,Crandall, Jack K.
, p. 2125 - 2130 (2007/10/02)
Allenyl halides of structure (CH3)2C=C=CH(CH2)nX with n=3-6 have been prepared and reacted with n-Bu3SnH to generate the corresponding radicals for examination of the cyclization reactions of these reactive intermediates.The observed hydrocarbon products indicate that cyclization occurs for the n=3,4, and 5 radicals but not for the n=6 species.The n=3 radical isomerizes very efficiently by intramolecular addition to the sp carbon of the allene group.The n=5 intermediate reacts relatively slowly by attack at the near sp2 carbon.Both cyclization modes are observed for the n=4 species.The details of these radical cyclizations are discussed.
A New Reducing System: Calcium Metal in Amines. Reduction of Aromatic Hydrocarbons
Benkeser, Robert A.,Belmonte, Frank G.,Kang, Jahyo
, p. 2796 - 2802 (2007/10/02)
A new reducing system consisting of calcium dissolved in a mixture of amines (methylamine-ethylenediamine) is described.Representative aromatic hydrocarbons have been reduced by this new reagent largely to monoalkenes.Hydrocarbons like tetralin, m- and p-xylene, and indan are reduced in excellent yields by the calcium system to a crude product containing 88percent or better of a single alkene.A new technique involving oxymercuration-demercuration is used to purify two of the monoalkene isomer mixtures obtained in these reductions.Unexpectedly, durene is reduced by the calcium reagent to 1,2,4,5-tetramethyl-1,4-cyclohexadiene in excellent yield.Likewise anthracene is reduced in one step to 1,2,3,4,5,6,7,8,9,10-decahydroanthracene.Experiments designed to elucidate why the calcium system does not reduce durene or anthracene to monoalkenes are described.Similarities and differences between the calcium-amine and the lithium-amine reducing systems are discussed.
Some studies on the solvolysis of 1-chloro-1-alkyl cycloalkanes
Ranganayakulu, K.,Vasumathi Devi, M.,Balaji Rao, R.,Rajeswari, K.
, p. 1484 - 1489 (2007/10/02)
The effect of the bulk of the sidechain on the rate of solvolysis of 1-alkyl cyclopentyl, cyclohexyl, and cycloheptyl chlorides has been studied.With the exception of the t-butyl systems, the ratio of solvolysis rates for the three ring systems falls in a given series.The slower rate of solvolysis in the six-membered ring system may be due to an extra activation energy contribution caused by the conversion of a neutral chair form to the twist boat or half chair conformation, prior to the actual solvolysis.In the case of five- and seven-membered ring systems the formation of an intermediate carbonium ion is sterically favoured (I-strain or eclipsing interaction) consistent with earlier findings.The faster rate of solvolysis of 1-t-butylcycloalkyl chlorides is likely due to a rearrangement reaction where alkyl participation enhances the rate of solvolysis.
