75-19-4Relevant articles and documents
Three-Component [1 + 1 + 1] Cyclopropanation with Ruthenium(II)
Jankins, Tanner C.,Fayzullin, Robert R.,Khaskin, Eugene
supporting information, p. 2609 - 2617 (2018/08/21)
We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal-catalyzed carbene attack on olefins. Under the current protocol, various alcohols and esters are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C-C bonds, three or two new chiral centers and one new quaternary carbon center. Twenty-two examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multistep, linear routes that proceed with overall low yields and poor control of stereochemistry. Commercially available Ru(II) dehydrogenation catalysts, that were recently developed for the dehydrogenative synthesis of esters and amides from alcohol and amine substrates, were used in the reaction, with the best catalyst showing excellent activity at 0.2-1 mol % catalyst loading. Mechanistic investigation showed that in the case of alcohol substrates, the catalyst is only responsible for the first dehydrogenation step, and that the identity of the base and the countercation is crucial in achieving high yields. The catalyst is also required for the cyclopropanation of esters, although no dehydrogenation can proceed in this case, suggesting that substrates sensitive to H2 may be acylated prior to reaction.
Nickel-Catalyzed Cyclopropanation with NMe4OTf and nBuLi
Künzi, Stefan A.,Sarria Toro, Juan Manuel,Den Hartog, Tim,Chen, Peter
supporting information, p. 10670 - 10674 (2015/09/02)
Nickel was identified as a catalyst for the cyclopropanation of unactivated olefins by using in situ generated lithiomethyl trimethylammonium triflate as a methylene donor. A mechanistic hypothesis is proposed in which the generation of a reactive nickel carbene explains several interesting observations. Additionally, our findings shed light on a report by Franzen and Wittig published in 1960 that had been retracted later owing to irreproducibility, and provide a rational basis for the systematic development of the reaction for preparative purposes as an alternative to diazomethane or Simmons-Smith conditions.
Accuracy of calculations of heats of reduction/hydrogenation: Application to some small ring systems
Wiberg, Kenneth B.
, p. 10393 - 10398 (2013/01/15)
The enthalpies of reduction of carbonyl compounds and hydrogenation of alkenes have been calculated at the HF, B3LYP, M06, MP2, G3, G4, CBS-QB3, CBS-APNO, and W1BD levels and, in the case of the first four methods, using a variety of basis sets up to aug-cc-pVTZ. The results are compared with the available experimental data, and it is found that the compound methods are generally more satisfactory than the others. Large basis sets are usually needed in order to reproduce experiments. Some C-C bond hydrogenolysis reactions also have been examined including those of bicycloalkanes and propellanes. In addition, the dimerization of the remarkably strained bicyclo[2.2.0]hex(1,4)ene was studied. The reaction forming a pentacyclic propellane was calculated to have ΔH = -57 kcal/mol, and the cleavage of the propellane to give a diene had ΔH = -71 kcal/mol. The strain energies of these compounds were estimated.
GASEOUS DIELECTRICS WITH LOW GLOBAL WARMING POTENTIALS
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, (2010/12/31)
A dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about ?20° C. to about ?273° C.; non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL; and a dielectric strength greater than air.
Azo-coupling and reduction of cyclopropanediazonium ions in the reactions with polyhydroxyarenes and aminophenols
Shulishov,Klimenko,Korolev,Kostyuchenko,Okonnishnikova,Tomilov
experimental part, p. 1703 - 1711 (2011/04/23)
A reaction of cyclopropanediazonium ion, generated by decomposition of N-cyclopropyl-N-nitrosourea upon treatment with potassium or cesium carbonates, with various poly-hydroxyarenes and aminophenols has been studied. The reaction of azo-coupling proceeds with phloroglucinol, resorcinol, 3-methoxy- and 3-aminophenol giving rise to mono-, bis-, and tris(cyclopropylazo)arenes as the major products. Oxidizable phenols such as hydro-quinone, 2-methoxy-, 4-amino-, and 2-aminophenol give products of radical transformations with participation of cyclopropyl radical.
Process for producing lower olefins by using multiple reaction zones
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Page/Page column 4, (2008/06/13)
The present invention provides a process for producing lower olefins by catalytic cracking a feedstock comprising an olefins-enriched mixture containing C4 or higher olefins and optionally an organic oxygenate compound. The technical problem mainly addressed in the present invention is to overcome the defects presented in the prior art including low yield and selectivity of lower olefins as the target products, and short regeneration period of catalyst. The present process, which is carried out under the conditions of catalytic cracking olefins and adopts as a feedstock an olefins-enriched mixture containing one or more C4 or higher olefins and optionally an organic oxygenate compound, comprises the steps of: a) letting the feedstock firstly enter a first reaction zone to contact with a first crystalline aluminosilicate catalyst having a SiO2/Al2O3 molar ratio of at least 10, to thereby produce a first reaction effluent containing lower olefins; b) letting the first reaction effluent enter in turn at least one second reaction zone to contact with a second crystalline aluminosilicate catalyst having a SiO2/Al2O3 molar ratio of at least 10, to thereby produce a second reaction effluent containing lower olefins; and c) separating lower olefins from the second reaction effluent; wherein the reaction temperatures in the first and second reaction zones are controlled. The present process, which desirably solves the above technical problem, can be used in industrial production of lower olefins.
Product selectivity in the electroreduction of thioesters
We?wer,Olivero,Du?ach
, p. 1709 - 1714 (2007/10/03)
The electroreduction of differently substituted aromatic and aliphatic thioesters (RCOSR′) led to regioselective reactions depending on the nature of the substituents. Thus, the cleavage between the carbonyl group and the SR′ group afforded α-diketones an
Stable ethylene inhibiting compounds and methods for their preparation
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Page 8, (2008/06/13)
A method to inhibit the ethylene response in plants with cyclopropene compounds by first generating stable cyclopropane precursor compounds and then converting these compounds to the gaseous cyclopropene antagonist compound by use of a reducing or nucleophilic agent.
Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
, p. 402 - 415 (2007/10/03)
Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
The γ-silicon effect on solvolyses of the 3-(aryldimethylsilyl)propyl system
Fujio, Mizue,Nakashima, Tohru,Fujiyama, Ryoji,Kim, Hyun-Joong,Tsuno, Yuho
, p. 612 - 615 (2007/10/03)
The γ-silicon effects in solvolyses were studied mechanistically on 3-(aryldimethylsilyl)propyl tosylates in various solvents based on the substituent effects. The mechanism can be described as competing reactions of the γ-silyl-assisted (kSi) and the solvent-assisted (ks) pathways. Copyright
