287-23-0Relevant academic research and scientific papers
Photodissociation of Tetramethylene Sulfoxide at 193 and 248 nm in the Gas Phase
Wu, Fei,Chen, Xirong,Weiner, Brad R.
, p. 17380 - 17385 (1995)
The 193 and 248 nm photodissociation of tetramethylene sulfoxide (TMSO) in the gas phase has been investigated by using laser spectroscopic techniques.The vibrational state distributions of the nascent SO(X3Σ-) photofragment following irradiation at 193 and 248 nm have been measured by using laser-induced fluorescence (LIF) spectroscopy on the B3Σ- - X3Σ- transition.These vibrational state distributions can be characterized as Boltzmann with vibrational temperatures of 1250 +/- 60 and 1220 +/- 60 K for the 193 and 248 nm photolyses, respectively.Assuming that the SO photofragment is produced in concert with a 1,4-tetramethylene diradical, the vibrational state distribution obtained in the 193 nm photolysis agrees well with an energy disposal model, in which the full reaction exoergicity is statistically partitioned among all the products' degrees of freedom.The quantum yield for SO(X3Σ-) production at 193 nm, Φ193SO = 0.47 +/- 0.20, has been obtained by comparison with SO2 photolysis.For the 248 nm photodissociation, the experimentally obtained vibrational state distribution can be best described by a variant statistical model assuming three-body fragmentation; i.e. the products are an SO fragment and two ethylene molecules.The quantum yield for SO(X3Σ-) production at 248 nm is Φ248SO = 0.44 +/- 0.19.The OH photofragment has been detected during both the 193 and 248 nm photolyses of TMSO.The rotational state distributions of the OH(X2Π, ν'' = 0) fragment have been determined by LIF spectroscopy using the A2Σ-X2Π transition.The hydroxyl rotational temperatures can be characterized as 600 +/- 50 and 510 +/- 40 K following photolysis of TMSO at 193 and 248 nm, respectively.Mechanisms for the production of both SO and OH are discussed.
The Photocycloaddition of Acetylacetone with Naphthols and their Methyl Ethers
Chow, Yuan L.,Buono-Core, Gonzalo E.,Liu, Xiao-Yun,Itoh, Kuniaki,Qian, Ping
, p. 913 - 915 (1987)
Whereas irradiation of a mixture of a naphthol (or its methyl ether) and acetylacetone with excitation of the naphthol component leads to no reaction, irradiation of a similar mixture with excitation of the acetylacetone component leads to its cycloaddition to the naphthalene derivative to give a cyclobutane as the primary photoproduct.
Exploring C(sp3)–C(sp3) reductive elimination from an isolable iron metallacycle
Joannou, Matthew V.,Darmon, Jonathan M.,Bezdek, Máté J.,Chirik, Paul J.
, p. 308 - 317 (2019/01/04)
A six-coordinate iron metallacyclopentane, (phen)2Fe(CH2)4, supported by two 1,10-phenanthroline (phen) ligands, has been synthesized and structurally and spectroscopically characterized. The complex is diamagnetic and an idealized octahedral geometry was observed in the solid state. The electronic structure of (phen)2Fe(CH2)4 was determined by a combination of X-ray diffraction, M?ssbauer spectroscopy, and DFT analyses and is best described as a low-spin Fe(III) center antiferromagnetically coupled to a radical anion delocalized equally over both phen ligands. The reactivity of (phen)2Fe(CH2)4 under different conditions was explored. Thermolysis or photolysis promoted elimination reactions and mixtures of isomeric butenes and butane were observed. Reactions of (phen)2Fe(CH2)4 with ethylene and isoprene yielded 3% and 11% of reductive elimination product cyclobutane, respectively, along with butane and butene isomers. Addition of π-accepting ligands such as carbon monoxide, maleic anhydride, or 1,4-benzoquinone to (phen)2Fe(CH2)4 promoted C(sp3)-C(sp3) reductive elimination as judged by high selectivity for cyclobutane formation. Two electron oxidation of (phen)2Fe(CH2)4 with two equivalents of ferrocenium tetraphenylborate also exclusively yielded cyclobutane in 95% yield. The electronic structure and reactivity of related bis(bipyridine) iron dialkyl compounds previously isolated by Kochi and co-workers were also revisited and their electronic structures revised based on structural, spectroscopic and computational data.
Palladium-Catalyzed, Norbornene-Mediated, ortho-Amination ipso-Amidation: Sequential C-N Bond Formation
Whyte, Andrew,Olson, Maxwell E.,Lautens, Mark
supporting information, p. 345 - 348 (2018/01/27)
A palladium-catalyzed, norbornene-mediated ortho- and ipso-C-N bond-forming Catellani reaction is reported. This reaction proceeds through a sequential intermolecular amination followed by intramolecular cyclization of a tethered amide. The products, ortho-aminated dihydroquinolinones, were generated in moderate to good yields and are present in bioactive molecules. This work highlights the challenge of competing intra- vs intermolecular palladium-catalyzed processes.
Inter-conversion of light olefins on ZSM-5 in catalytic naphtha cracking condition
Liu, Dan,Choi, Won Choon,Kang, Na Young,Lee, You Jin,Park, Hun Soo,Shin, Chae-Ho,Park, Yong-Ki
, p. 52 - 66 (2014/03/21)
The inter-conversion of light olefins over four types of HZSM-5 based catalysts under cracking conditions was investigated systematically and various methods including XRD, Ar adsorption-desorption, NH3-TPD, 27Al and 31P MAS-NMR were used to characterize the effects of P modification and steaming on ZSM-5. Regardless the types of catalyst, the same behaviors of light olefin inter-conversion were observed only depending on conversion of light olefins. Also, the conversion and selectivity were not influenced by the presence of hydrogen, suggesting that light paraffins were mainly produced from hydrogen transfer during cracking rather than hydrogenation of light olefins. It can be suggested that the inter-conversion of light olefins occurs through oligomerization of light olefins and then re-cracking of the oligomerized products. To guarantee high light olefin yield in catalytic naphtha cracking, it is strongly required to suppress oligomerization of light olefins during catalytic cracking.
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.
Total synthesis and revised structure of biyouyanagin A
Nicolaou,Sarlah, David,Shaw, David M.
, p. 4708 - 4711 (2008/02/10)
(Chemical Equation Presented) It all adds up: A 12-step total synthesis of biyouyanagin A, an inhibitor of HIV replication, has revealed its structure, rendered it available for biological investigations, and allows the synthesis of analogues. The convergent synthesis involves two cascade sequences and a remarkably selective [2+2] cycloaddition reaction to forge the cyclobutane ring of the target molecule in the ultimate step.
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.
Tricyclic inhibitors of the GPIIb IIIa receptor
-
, (2008/06/13)
A tricylic benzodiazepine derivative that acts as a nonpeptidyl platelet aggregation inhibitor is provided. This inhibitor potently inhibits fibrinogen binding to the GPIIb IIIa receptor and is provided in therapeutic compositions for the treatment of diseases for which blocking platelet aggregation is indicated. These nonpeptidyl inhibitors are provided in combination with thrombolytics and anticoagulants.
Tricyclic inhibitors of the vitronectin receptor
-
, (2008/06/13)
A tricylic benzodiazepine derivative that acts as a nonpeptidyl platelet aggregation inhibitor is provided. This inhibitor potently inhibits fibrinogen binding to the GPIIb IIIa receptor and is provided in therapeutic compositions for the treatment of diseases for which blocking platelet aggregation is indicated. These nonpeptidyl inhibitors are provided in combination with thrombolytics and anticoagulants.
