- Associative Covalent Relay: An Oxadiazolone Strategy for Rhodium(III)-Catalyzed Synthesis of Primary Pyridinylamines
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A relay formalism is proposed herein for categorizing the interplay among reactants, target product, and catalytic center in transition-metal catalysis, an important factor that can dictate overall catalysis viability and efficiency. In this formalism, transition-metal catalysis can proceed by dissociative relay, associative covalent relay, and associative dative relay modes. An intriguing associative covalent relay process operates in rhodium(III)-catalyzed oxadiazolone-directed alkenyl C?H coupling with alkynes and allows efficient access to primary pyridinylamines. Although the primary pyridinylamine synthesis mechanism is posteriori rationalized, the relay formalism formulated herein can provide an important mechanistic conceptual framework for future catalyst design and reaction development.
- Yu, Xiaolong,Chen, Kehao,Wang, Qi,Guo, Shan,Zha, Shanke,Zhu, Jin
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supporting information
p. 5222 - 5226
(2017/04/27)
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- Synthesis and characterization of an A2BC type phthalocyanine and its visible-light-responsive photocatalytic H2 production performance on graphitic carbon nitride
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A highly asymmetric A2BC type zinc phthalocyanine (Zn-di-PcNcTh) has been designed and synthesized. The Zn-di-PcNcTh used a π electron rich thiophene ring in place of the benzenoid rings of phthalocyanine which acted as an electron donor, diphenylphenoxy substituents to retard aggregation and a carboxyl-naphthalene unit as an electron acceptor. The asymmetric phthalocyanine shows a strongly split Q-band and wide spectral absorption in the visible/near-IR light region, which can extend the spectral response region of graphitic carbon nitride (g-C3N4) from ~450 nm to more than 800 nm. By using it as a sensitizer of 1.0 wt% Pt-loaded graphitic carbon nitride (g-C3N4), the experimental results indicate that Zn-di-PcNcTh-Pt/g-C3N4 shows a H2 production efficiency of 249 μmol h-1 with an impressive turnover number (TON) of 9960.8 h-1 under visible light (λ ≥ 420 nm) irradiation, much higher than that of pristine Pt/g-C3N4. Owing to the introduction of a highly bathochromic shift of 3,4-dicyanothiophene and the valuable "push-pull" effect from the thiophene (electron donor) to the carboxyl-naphthalene (electron acceptor) unit, Zn-di-PcNcTh/g-C3N4 gives an extremely high apparent quantum yield (AQY) of 2.44%, 3.05%, and 1.53% under 700, 730, and 800 nm monochromatic light irradiation, respectively, under optimized photocatalytic conditions.
- Guo, Yingying,Song, Shuaishuai,Zheng, Ya,Li, Renjie,Peng, Tianyou
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supporting information
p. 14071 - 14079
(2016/11/05)
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- Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism
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A minimal cell can be thought of as comprising informational, compartment-forming and metabolic subsystems. To imagine the abiotic assembly of such an overall system, however, places great demands on hypothetical prebiotic chemistry. The perceived differences and incompatibilities between these subsystems have led to the widely held assumption that one or other subsystem must have preceded the others. Here we experimentally investigate the validity of this assumption by examining the assembly of various biomolecular building blocks from prebiotically plausible intermediates and one-carbon feedstock molecules. We show that precursors of ribonucleotides, amino acids and lipids can all be derived by the reductive homologation of hydrogen cyanide and some of its derivatives, and thus that all the cellular subsystems could have arisen simultaneously through common chemistry. The key reaction steps are driven by ultraviolet light, use hydrogen sulfide as the reductant and can be accelerated by Cu(I)-Cu(II) photoredox cycling.
- Patel, Bhavesh H.,Percivalle, Claudia,Ritson, Dougal J.,Duffy, Colm D.,Sutherland, John D.
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p. 301 - 307
(2015/04/14)
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- PROCESS FOR PRODUCING ISOTHIAZOLE DERIVATIVE
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A process for producing 3,4-dichloro-5-cyanoisothiazole represented by a general formula (3): the process comprising: reacting a nitrile compound represented by a general formula (1): (wherein “n” denotes an integer of 0 to 2), with sulfur chloride represented by a general formula (2): [Chemical Formula 18] SmCl2 ??(2) (wherein “m” represents an integer of 1 to 2), or a mixture thereof in an aprotic polar solvent. There is provided a process for producing 3,4-dichloro-5-cyanoisothiazole, which is capable of suppressing by-production of a waste, without using a raw material having a having a strong toxicity; and is capable of providing a product having a higher purity in a high yield and efficiency in an industrial scale, in a simple manner.
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Page/Page column 6
(2012/03/10)
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- 2 H-azirines from a concerted addition of alkylcarbenes to nitrile groups
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Photolysis of aziadamantanes in the presence of fumaronitrile (FN) unexpectedly afforded conjugated 2H-azirines resulting from addition of the carbene to the CN triple bond. This represents the first example of a direct azirine formation starting from an alkylcarbene for which a concerted pathway is postulated. The novel outcome of the reaction is favored by the prior formation of a carbene-alkene complex, a type of adduct that only recently has been described.
- Knoll, Wolfgang,Mieusset, Jean-Luc,Arion, Vladimir B.,Brecker, Lothar,Brinker, Udo H.
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supporting information; experimental part
p. 2366 - 2369
(2010/07/13)
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- Synthesis, structures, and reactivity of kinetically stabilized anthryldiphosphene derivatives
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The first stable anthryldiphosphenes, 1 and 2, were synthesized by utilizing kinetic stabilization of 2,4,6- tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl] phenyl (Bbt) groups, and were characterized by spectroscopic and X-ray crystallographic analyses. The UVvisible spectroscopic data suggested the electronic communication between the anthryl moiety and the P=P unit. It was found that TbtP=P(9- Anth) (1a: 9-Anth = 9-anthryl) showed weak fluorescence in hexane solution. Furthermore, the reactivities of anthryldiphosphene 1 with a chromium complex, chalcogenation reagents, a diene, and electron-deficient olefins have been revealed.
- Tsurusaki, Akihiro,Nagahora, Noriyoshi,Sasamori, Takahiro,Matsuda, Kazunari,Kanemitsu, Yoshihiko,Watanabe, Yasuaki,Hosoi, Yoshinobu,Furukawa, Yukio,Tokitoh, Norihiro
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body text
p. 456 - 478
(2010/07/04)
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- Olefin self-cross-metathesis catalyzed by the second-generation Grubbs carbene complex in room temperature ionic liquids
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Olefin self-cross-metathesis (CM) reactions catalyzed by the second-generation Grubbs carbene complex have been compared in dichloromethane and two kinds of selected room temperature ionic liquids (RTILs). Both the catalyst and the ionic liquids could be simply recovered and reused for at least four cycles just with a little drop in activity. Significant enhancements in the reactivity, yield and reaction rate were achieved.
- Ding, Xiong,Lv, Xianhai,Hui, Bin,Chen, Zhijuan,Xiao, Minliang,Guo, Baoshou,Tang, Wenming
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p. 2921 - 2924
(2007/10/03)
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- Highly active phosphine-free carbene ruthenium catalyst for cross-metathesis of acrylonitrile with functionalized olefins
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The carbene ruthenium complex [1,3-bis(2,6-dimethylphenyl)-4,5- dihydroimidazol-2-ylidene](C5H5N)2(Cl) 2RuCHPh (8) was prepared by the reaction of [1,3-bis (2,6-dimethylphenyl)-4,5-dihydroimidazol-2-ylidene](PPh3)(Cl) 2RuCHPh (7) with pyridine and used as a highly effective catalyst for the cross-metathesis of acrylonitrile with various functionalized olefins.
- Bai, Chen-Xi,Zhang, Wen-Zhen,He, Ren,Lu, Xiao-Bing,Zhang, Zhi-Qiang
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p. 7225 - 7228
(2007/10/03)
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- Lewis-acid assisted cross metathesis of acrylonitrile with functionalized olefins catalyzed by phosphine-free ruthenium carbene complex
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The exchange of the PPh3 ligand in the complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](PPh 3)-(Cl)2Ru=CHPh (7) for a pyridine ligand at ambient temperature leads to the formation of the stable phosphine-free carbene ruthenium complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene] (C5H5N)2(Cl)2 Ru=CHPh (8). The resulted ruthenium complex exhibits highly catalytic activity for the cross metathesis of acrylonitrile with various functionalized olefins under mild conditions, and its activity can be further improved by the addition of a Lewis acid such as Ti(O′Pr)4. In the mixture products, the Z-isomer predominates. The Royal Society of Chemistry 2005.
- Bai, Chen-Xi,Lu, Xiao-Bing,He, Ren,Zhang, Wen-Zhen,Feng, Xiu-Juan
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p. 4139 - 4142
(2007/10/03)
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- Microwave spectra and molecular structures of (Z)-pent-2-en-4-ynenitrile and maleonitrile
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Accurate equilibrium structures have been determined for (Z)-pent-2-en-4-ynenitrile (8) and maleonitrile (9) by combining microwave spectroscopy data and ab initio quantum chemistry calculations. The microwave spectra of 10 isotopomers of 8 and 5 isotopomers of 9 were obtained using a pulsed nozzle Fourier transform microwave spectrometer. The ground-state rotational constants were adjusted for vibration-rotation interaction effects calculated from force fields obtained from ab initio calculations. The resultant equilibrium rotational constants were used to determine structures that are in very good agreement with those obtained from high-level ab initio calculations (CCSD(T)/cc-pVTZ). The geometric parameters in 8 and 9 are very similar; they also do not differ significantly from the all-carbon analogue, (Z)-hex-3-ene-1,5-diyne (7), the parent molecule for the Bergman cyclization. A small deviation from linearity about the alkyne and cyano linkages is observed for 7-9 and several related species where accurate equilibrium parameters are available. The data on 7-9 should be of interest to radioastronomy and may provide insights on the formation and interstellar chemistry of unsaturated species such as the cyanopolyynes.
- Halter,Fimmen,McMahon,Peebles,Kuczkowski,Stanton
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p. 12353 - 12363
(2007/10/03)
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- Facile Synthesis of 13C-2-Butenedinitrile and Regiospecifically Labeled 13C,15N-Pyridoxines
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Syntheses of -2-butenedinitrile in a one-pot process and pyridoxines regiospecifically multi-labeled with carbon-13 and nitrogen-15 are described.
- Hoshino, Jun-ichi,Yamamoto, Yukio,Hasegawa, Takeshi,Takahashi, Sho,Sawada, Seiji
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p. 1939 - 1941
(2007/10/02)
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- The Diels-Alder Reaction of 2,5-Dialkylfurans and Fumaronitrile Revisited
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The equilibrium reactions of furan and 2,5-dialkyl derivatives with fumaronitrile were investigated under standard conditions (3.0*10-4M) at four different temperatures in chloroform-d as solvent.Plots of lnK against 1/T were linear for each member of the series.The results show that the equilibrium concentration of adduct is sensitive to substituents.At equilibrium, there is a greater proportion of adduct derived from 2,5-dimethylfuran than from furan itself.However, as the length of the substituent chains is increased, the proportion of adduct decreases.Similar trends are also apparent from a more limited study of the equilibria in methanol-d4 and acetone-d6 as solvents.The concentrations of adduct in the equilibrium mixtures are highest in chloroform-d and lowest in acetone-d6.AM1 calculations are reported for model adduct structures.
- Cook, Michael J.,Cracknell, Steven J.
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p. 12125 - 12132
(2007/10/02)
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- Role of Contact and Solvent-Separated Radical Ion Pairs in the Diffusional Quenching of trans-Stilbene Excited Singlet State by Fumaronitrile
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Picosecond absorption spectroscopy is used to examine the question of wether contact radical ion pairs (CRIP) or solvent-separated radical ion pairs (SSRIP) are formed upon the quenching, by electron transfer, of the first excited singlet state of trans-stilbene (S1) by fumaronitrile (FN).Prior to these experiments, it was generally believed that for exothermic reactions in polar solvents, SSRIP are formed upon quenching by electron transfer.However the present experiments reveal that the quenching of S1 by FN in acetonitrile leads to the formation of CRIP.To establish the nature of the radical ion pair formed upon electron transfer, the kinetics for the decay of the CRIP and the SSRIP are established.
- Peters, Kevin S.,Lee, Joseph
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p. 8941 - 8945
(2007/10/02)
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- The Reaction of Wittig Reagents with Selenium. Formation of Selenoaldehydes
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The reaction of Wittig reagents with elemental selenium gave the corresponding selenoaldehydes which further reacted with other Wittig reagents to give the corresponding dimeric olefins in good yields.The selenoaldehydes formed afforded corresponding adducts by the reaction with dienes.These selenoaldehydes obtained by retro Diels-Alder reaction were also found to react with Wittig reagents to give the corresponding olefins in good yields.
- Okuma, Kentaro,Komiya, Yasuo,Kaneko, Isao,Tachibana, Yuji,Iwata, Eiji,Ohta, Hiroshi
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p. 1653 - 1657
(2007/10/02)
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- Intrinsic Rate of Electron Transfer in the Diffusional Quenching of trans-Stilbene S1 by Fumaronitrile
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The quenching of the first excited singlet state of trans-stilbene (S1) by fumaronitrile in acetonitrile has been examined by picosecond laser spectroscopy.From the time dependence of the rate constant for the quenching of S1, the intrinsic rate of the electron transfer can be separated from the diffusional contribution.The rate of electron transfer is ket = 1.9E12 M-1 s-1.From the time dependence of the formation of the resulting ion pair, it is concluded that the electron transfer occurs when the molecules are in contact.
- Angel, Stephen A.,Peters, Kevin S.
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p. 713 - 717
(2007/10/02)
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- Reactions of Wittig Reagents with Episulfides or Elemental Sulfur
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The reactions of Wittig reagents with episulfides gave symmetrical olefins and triphenylphosphine sulfide in moderate yields.The same olefins were obtained by reactions of Wittig reagents with elementar sulfur.These reactions might proceed through thiocarbonyl intermediates, the existence of which was confirmed by Diels-Alder reactions with dienes.
- Okuma, Kentaro,Tachibana, Yuji,Sakata, Jun-ichi,Komiya, Takashi,Kaneko, Isao,et al.
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p. 4323 - 4328
(2007/10/02)
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- Elimination reactions of β-Cyano Thioethers: Evidence for a Carbanion Intermediate and a Change in Rate-Limiting Step
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The addition reactions of thiol anions to form adducts with acrylonitrile (1), 1-chloroacrylonitrile (2), and fumaronitrile (3) and the corresponding elimination reactions were examined in aqueous solution, generally containing 8.3percent Me2SO at 25 deg C.Deuterium exchange into the methanethiol and thiosalicylate adducts of 1 is faster than elimination.Deuterium exchange causes biphasic kinetics for elimination reactions in D2O of the p-nitrothiophenol, but not of the pentafluorothiophenol, adducts 1 and 2.The kinetic solvent deuterium isotope effects of knHOH/knDOD = 2.0 for addition of thiosalicylate to form 3 and 1.1-1.2 for addition of β-mercaptoethanol and thioacetic acid anions to form 1 are smaller than the product discrimination isotope effects of kH/kD = 3.2, 2.8 and 3.2 for these reactions.These differences show that the reactions proceed through a carbanion intermediate that is protonated faster than it expels basic thiol anions.These results exclude a concerted mechanism for addition-elimination with a concurrent, separate exchange reaction.The solvent kinetic deuterium isotope effect is 3.9 for the addition of thionitrobenzoate dianion to form 3.Buffer catalysis of elimination becomes more significant with more acidic leaving groups and is larger for 3 than for 1 with a given leaving group.The results show that the rate-limiting step changes from addition-elimination of the thiol anion to proton transfer with decreasing pKa of the thiol; the same change is favored by addition of CN to the α-position for a given thiol.The effect of the α-CN group is attributed to conjugation with the developing double bond in the transition state for elimination.The Broensted slope is β = 0.90 for rate-limiting deprotonation of the pentafluorothiophenol adduct 3 and Broensted-type plots against the pKa of the leaving group have slopes of β1g = -0.25 and -0.54 for predominantly rate-limiting deprotonation and leaving group expulsion, respectively.
- Fishbein, James C.,Jencks, William P.
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p. 5075 - 5086
(2007/10/02)
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- FLASH VACUUM PYROLYSIS OF PYRIDAZINE N-OXIDES
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Flash vacuum pyrolysis of 6-unsubstituted pyridazine 1-oxides afforded nitriles and pyrroles. 6-Phenylpyridazine 1-oxides gave 2-phenyloxazole together with nitriles and pyrroles. 6-Methylpyridazine 1-oxide and 3,6-dimethylpyridazine 1-oxide afforded naphthalene and benzene, respectively, together with other products.The formation mechanism of these products was speculated.
- Ohsawa, Akio,Itoh, Takashi,Igeta, Hiroshi
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p. 2677 - 2681
(2007/10/02)
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- STEREOSELECTIVE SYNTHESIS OF TRANS OLEFINS BY THE REACTION OF WITTIG REAGENTS WITH SELENIUM. FORMATION OF SELENOCARBONYL COMPOUNDS.
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Wittig reagents were successfully changed to symmetrical olefins when treated with elemental selenium.The reaction proceeds through a selenocarbonyl intermediate, which existence was confirmed by Diels-Alder reaction.
- Okuma, Kentaro,Sakata, Jun-ichi,Tachibana, Yuji,Honda, Takumi,Ohta, Hiroshi
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p. 6649 - 6652
(2007/10/02)
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- Electron Affinities of Di- and Tetracyanoethylene and Cyanobenzenes Based on Measurements of Gas-Phase Electron-Transfer Equilibria
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The electron affinities of tetracyanoethylene, trans-1,2-dicyanoethylene, and eleven substituted benzonitriles as well as two naphthonitriles were determined by measurement of the electron-transfer equilibria A-+B=A+B- with a pulsed electron high ion source pressure mass spectrometer.Rate constants for exothermic electron transfer involving the cyano compounds were found to be near unit collision efficiency.The EA (tetracyanoethylene)=3.17 eV obtained in the present work is considerably higher than the 2.3 eV photodetachment value of Palmer and Lyons.The electron affinities of benzene and benzonitrile substituted by CN, CHO, and NO2 increase in the given order, while the order for nitrobenzene is CHO, CN, NO2.This reversal of order is explained on the basis of a larger attenuation of the ?-withdrawing effect relative to the field effect of substituents when the electron density in the ?* single-electron orbital is decreased.
- Chowdhury, Swapan,Kebarle, Paul
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p. 5453 - 5459
(2007/10/02)
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- Stereochemical Study on 1,3-Dipolar Cycloaddition Reactions of Heteroaromatic N-Ylides with Symmetrically Substituted cis and trans Olefins
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Stereochemistry of the cycloadditions of twenty-four heteroaromatic N-ylides with several symmetrically substituted cis and trans olefins has been investigated.Cyclic and acyclic cis olefins cycloadd to the anti form of the ylides in a highly endo-selective manner giving almost quantitative yields of stereospecific endo 3+2 cycloadducts.N-Ylides stabilized with a substituent of carbonyl type react with trans olefins to form mostly two stereoisomeric 3+2 cycloadducts to the anti form of the ylides.In most cases, they undergo the stereospecific interconversion through a retro cycloaddition process, the isomer ratios and the easiness of transfromation depending upon the nature and size of substituents on the five-membered ring which has been built up in the cycloaddition step.On the other hand, N-ylides stabilized with a substituent of noncarbonyl type react with trans olefins to give stereospecific and stereoselective 3+2 cycloadducts as single isomers which are assigned as the cycloadducts to the syn form of the ylides.
- Tsuge, Otohiko,Kanemasa, Shuji,Takenaka, Shigeori
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p. 3137 - 3157
(2007/10/02)
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- Production of Acrylonitrile and Other Unsaturated Nitriles from Alkenes and Alkynes
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Passage of unsaturated organic molecules trough a 13.56-MHz radio-frequency discharge, in the presence of cyanogen, results in the formation of unsaturated nitriles.Acrylonitrile was the major product from ethylene, propylene, acrolein, methyl vinyl ketone, or 1,1,1-trifluoropropylene. 1-Butene, 2-butene, and isobutylene gave mixtures of nitrile products with the CN situated at vinylic or allylic positions. 2-Butyne gave 1-cyanopropyne.Other compounds gave only low yields of nitriles and considerable polymer.The effects of power, pressure, flow rate, and ratios of reactants on the yields of acrylonitrile from propylene and cyanogen were studied.A typical power yield of acrylonitrile was 30 g kW-1 h-1.Maximum material yields of nitrile products were obtained at intermediate powers and pressures.The products are consistent with a reaction scheme involving attack of initially formed cyano radicals on the organic substrate.This step forms activated radical intermediates, which decay through elimination of an atom or group.The atom or group which is most weakly bound is preferentially lost.
- Henis, Neil B.,Miller, Larry L.
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p. 2526 - 2529
(2007/10/02)
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- AMMOXYDATION CATALYTIQUE DES HYDROCARBURES ET REACTIONS APPARENTEES. XXII. AMMOXYDATION DU BENZENE ET DU CYCLOHEXANE
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Benzene ammoxidation at 440-550 deg C/1 at. produces, on V-Mo, Ti-Mo, Bi-Mo (oxides) catalysts, unsaturated C4 (maleo and fumaronitriles) and C6 (mucononitrile and stereoisomers) dinitriles.These initial selectivities fall with increasing conversions, and C6 dinitriles disappear above 10percent conversion by thermal or catalytic degradation.The main initial stereoisomer cis-cis (mucononitrile) is consistent with a 1-2 attack of the aromatic ring, so far unknown in catalytic oxidations.Cyclohexane ammoxidation goes through the oxidative dehydrogenation to benzene and proceduces small amounts of C4 unsaturated dinitriles along with traces of C4, C5 and C6 saturated dinitriles coming from a different reaction path.In both cases, V-Mo and Ti-Mo are the best catalysts for dinitriles production; no C6 formed on Sn-Mo, Sb-Mo and Sn-Sb-Fe-catalysts.
- Simon, Gerard,Germain, Jean-Eugene
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p. 149 - 155
(2007/10/02)
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- Photochemical reactions of charge-transfer complexes. The irradiation of the charge-transfer complexes between 1,4-, 1,5-, and 2,3-dimethoxynaphthalenes and 1,2-dicyanoethylenes.
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The first part of this paper describes the experimental search for a donor which would complex preferentially one of the isomers of 1,2-dicyanoethylene.This involved measuring the association constants (KDAc) of the charge-transfer (ct) complexes of several dimethoxynaphthalenes (DMN) with maleonitrile (MN) and fumaronitrile (FN).From the measured KDAc, we found that MN complexes more strongly than FN with 1,4- and 1,5-DMN but that FN complexes more strongly with 2,3-DMN than does MN.These results are explained in terms of more than one favourable geometry for the ct complexes, since the donors are relatively large compared to the acceptors.Irradiation of the ct complexes between 1,4-, 1,5-, or 2,3-DMN and 1,2-dicyanoethylene led to isomerization of the olefins.The photostationary state depends on the absorption spectra of the ct complexes formed between the donor and the isomeric olefins.From spectroscopic and photo-CIDNP studies, we find evidence that the isomerization in polar solvents takes place via the triplet state of the olefin.The triplet is formed from the radical ion pair resulting after excitation of the ct complex.
- Wong, P.C.,Arnold, D.R.
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p. 918 - 927
(2007/10/02)
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- Structure-Reactivity Factors for Exciplex Isomerization of Quadricyclene and Related Compounds
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The quadricyclenes (1) and (3) are equally effective in exciplex isomerization although other cage hydrocarbons do not undergo efficient reaction when sensitized by aromatic fluorophores; irradiation of charge-transfer complexes of (1) and (3) and electron-deficient alkenes results in efficient valence but not geometrical isomerization.
- Jones, Guilford,Chiang, Sheau-Hwa,Becker, William G.,Greenberg, Don P.
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p. 681 - 683
(2007/10/02)
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- Production of maleonitrile
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Maleonitrile is obtained as a dominant product of the reaction between cyanoacetylene and hydrogen cyanide. The yield of maleonitrile is remarkably higher than that in any of known processes.
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