- ONE POT SYNTHESIS FROM THE ELEMENTS OF SYMMETRICAL AND UNSYMMETRICAL TRIARYL-PHOSPINES, -ARSINES AND -STIBINES BY THE SRN1 MECHANISM
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The reactions of elemental phosphorus, arsenic and antimony with sodium metal in liquid ammonia form "M-3" species that react with haloarenes under irradiation to form symmetrical triaryl derivatives of these metals by the SRN1 mechanism in fair to good yields.Further reaction with sodium metal gives a derivative nucleophile (diarylphosphide and diarylarsenide ions) that reacts with another haloarene under irradiation to form unsymmetrical phosphines and arsines.
- Bornancini, Esteban R.,Alonso, Ruben A.,Rossi, Roberto A.
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Read Online
- Highly stereoselective synthesis of cyclopropyl heterocycles via cyclopropanation of olefin with arsonium salt
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(Chemical Equation Presented) An efficient and highly stereoselective approach for the preparation of highly functionalized cyclopropyl heterocycles via the cyclopropanation of olefines with arsonium salts in the presence of KF 2H2O has been developed.
- Ren, Zhongjiao,Cao, Weiguo,Tong, Weiqi,Chen, Jie,Wang, Changqing
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Read Online
- DEOXYGENATION OF TRIPHENYLARSINE OXIDE TO TRIPHENYLARSINE BY LOW VALENT TITANIUM
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Low valent titanium was used to deoxygenate triphenylarsine oxide to triphenylarsine.
- Xing, Yi De,Hou, Xue Long,Huang, Nai Zheng
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Read Online
- Organic Electrochemistry: Expanding the Scope of Paired Reactions
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Paired electrochemical reactions allow the optimization of both atom and energy economy of oxidation and reduction reactions. While many paired electrochemical reactions take advantage of perfectly matched reactions at the anode and cathode, this matching of substrates is not necessary. In constant current electrolysis, the potential at both electrodes adjusts to the substrates in solution. In principle, any oxidation reaction can be paired with any reduction reaction. Various oxidation reactions conducted on the anodic side of the electrolysis were paired with the generation and use of hydrogen gas at the cathode, showing the generality of the anodic process in a paired electrolysis and how the auxiliary reaction required for the oxidation could be used to generate a substrate for a non-electrolysis reaction. This is combined with variations on the cathodic side of the electrolysis to complete the picture and illustrate how oxidation and reduction reactions can be combined.
- Moeller, Kevin D.,Wu, Tiandi
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supporting information
p. 12883 - 12890
(2021/05/07)
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- Fundamental Study on Arsenic(III) Halides (AsX3; X = Br, I) toward the Construction of C3-Symmetrical Monodentate Arsenic Ligands
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Arsenic ligands have attracted considerable attention in coordination chemistry. Arsenic(III) halides are the most important starting materials in the preparation of monodentate arsenic ligands. In this work, we optimized the synthetic methodologies of arsenic(III) halides (AsX3; X = Br, I) and examined the difference of their physical properties such as solubility to organic solvent and reactivity to nucleophiles. In addition, a wide variety of monodentate arsenic ligands were prepared with the obtained AsX3. Finally, the obtained monodentate arsenic ligands were utilized for copper-free Sonogashira cross-coupling reaction in the reaction system with porphyrin. The results showed that monodentate arsenic ligands have higher catalytic activity compared with triphenylphosphine because of the difference of the electronic features of lone pairs between arsenic and phosphorus atoms.
- Tanaka, Susumu,Konishi, Masafumi,Imoto, Hiroaki,Nakamura, Yuma,Ishida, Masatoshi,Furuta, Hiroyuki,Naka, Kensuke
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supporting information
p. 9587 - 9593
(2020/07/02)
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- A practical method for the generation of organoarsenic nucleophiles towards the construction of a versatile arsenic library
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Nucleophilic arsenic reagents were prepared in situ from a nonvolatile cyclooligoarsine. As-As bond cleavage of the cyclooligoarsine readily proceeded with anion sources. Various kinds of organoarsenic compounds were easily constructed in high yields by selecting anion sources and electrophiles. In comparison with conventional methods of As-C bond formation, a wide variety of organoarsenic compounds were safely and easily synthesized by using this method.
- Tanaka, Susumu,Imoto, Hiroaki,Kato, Takuji,Naka, Kensuke
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supporting information
p. 7937 - 7940
(2016/06/09)
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- Tail-to-tail dimerization of methyl acrylate in the presence of triphenylarsine ruthenium complexes
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Dimerization of methyl acrylate by ruthenium-based homogenous catalysts. The effect of the addition of supporting ligands on selectivity was studied. Conversion and selectivity were significantly affected by using triphenyl arsine. Possible reaction mechanism to achieve the tail to tail product was discussed. Catalytic dimerization of methyl acrylate by homogenous ruthenium catalysts was investigated. The effect of the addition of acidic additives, supporting ligands, polymerization inhibitor, and reaction conditions on the selectivity of dimerization was studied, and possible reaction mechanism was discussed. Conversion and selectivity were significantly affected by using triphenylarsine as supporting ligand. Under mild conditions, conversion up to 98% with good selectivity to tail-to-tail product was achieved.
- Behnia, Ava,Tamaddoni Jahromi, Bahareh,Nemati Kharat, Ali
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p. 3018 - 3025
(2015/10/20)
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- Chemoselective hydrogenation of nitroarenes and deoxygenation of pyridine N-oxides with H2 catalyzed by MoO2Cl2
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A chemoselective and highly efficient hydrogenation of nitroarenes and deoxygenation of pyridine N-oxides using a cheap and environmentally friendly H2/MoO2Cl2 system has been developed.
- Reis, Patrícia M.,Royo, Beatriz
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scheme or table
p. 949 - 952
(2009/05/27)
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- Reduction of tertiary phosphine oxides with DIBAL-H
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(Chemical Equation Presented) The reduction of tertiary phosphine oxides (TPOs) and sulfides with diisobutylaluminum hydride (DIBAL-II) has been studied in detail. An extensive solvent screen has revealed that hindered aliphatic ethers, such as MTBE, are optimum for this reaction at ambient temperature. Many TPOs undergo considerable reduction at ambient temperature and then stall due to inhibition. 31P and 13C NMR studies using isotopically labeled substrates as well as competition studies have revealed that the source of this inhibition is tetraisobutyldialuminoxane (TIBAO), which builds up as the reaction proceeds. TIBAO selectively coordinates the TPO starting material, preventing further reduction. Several strategies have been found to circumvent this inhibition and obtain full conversion with this extremely inexpensive reducing agent for the first time. Practical reduction protocols for these critical targets have been developed.
- Busacca, Carl A.,Raju, Ravinder,Grinberg, Nelu,Haddad, Nizar,James-Jones, Paul,Lee, Heewon,Lorenz, Jon C.,Saha, Anjan,Senanayake, Chris H.
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p. 1524 - 1531
(2008/04/12)
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- Highly stereoselective construction of spiro[cyclopropane-1,4′-pyrazolin-5′-one]with 4-arylidene-3-methyl-1-phenyl-pyrazolin-5-one and arsonium ylide
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A highly stereoselective synthesis of exo-spiro[cyclopropane-1,4′-pyrazolin-5′-one] from 4-arylidene-3-methyl-1-phenyl-pyrazolin-5-one and arsonium bromide in the presence of base has been achieved. The triphenylarsine-catalyzed cyclopropanation of 4-arylidene-3-methyl-1-phenyl-pyrazolin-5-one with bromide in the presence of NaHCO3 has also been studied. Both exo and endo isomers were formed in this reaction. The structures of the products were characterized by IR, MS, 1H NMR, elemental analysis, and X-ray diffraction analysis.
- Ren, Zhongjiao,Cao, Weiguo,Chen, Jie,Chen, Yali,Deng, Hongmei,Shao, Min,Wu, Danyi
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p. 5156 - 5161
(2008/09/21)
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- Ascorbic acid/iodine and triphenylphosphine/iodine as reducing agents for the As(V)=O group
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The scope of ascorbic acid/iodine and triphenylphosphine/iodine in methanol for the direct reduction of arsenic(V) compounds having the As=O group has been investigated. Ascorbic acid/iodine reduces arsonic acids, diphenylarsinic acid (but not dimethylarsinic acid), and triphenylarsine oxide. The rates of reduction depend on the electronic effects of the ligands bound to arsenic and on the hydrogen-bonding strength of the species, when present. When the As(V) compound has an -NH2 or an -NH3+ group, the reduction product reacts with a ketonic form of dehydroascorbic acid, giving condensation product(s). Triphenylphosphine/iodine reduced slowly the zwitterionic o-aminophenylarsonic acid but reduced faster the hydrochloric acid salt of the same acid. It reduced dimethylarsinic acid as well because the powerful electron-withdrawing Ph3P+coordinated to As=O seems to outweigh the electronic and hydrogen bonding effects. Copyright Taylor & Francis Group, LLC.
- Sideris, Theodore D.,Ioannou, Panayiotis V.
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p. 1017 - 1030
(2007/10/03)
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- Two-step synthesis of triarylmetals (As, Sb, Bi) starting from the metal oxides and 2,6-dimethoxybenzenethiol
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Reported here is a new synthetic method of triarylmetals MAr3 (M = As, Sb, Bi). It is composed of two-step reactions starting from the metal oxides: (1) A reaction of the metal oxide with 2,6-dimethoxybenzenethiol ΦSH [Φ = 2,6-(MeO)2C6H3] in the presence of acid to give the thiolatometals M(SΦ)3, and (2) A reaction of M(SΦ)3 with organolithium reagent LiAr to give MAr3 (Ar = Ph, 4-MeC6H4, 4-Me2NC6H4, Φ). Since ΦSH is odorless and crystalline, most of it can be recovered after the reactions without difficulty for repeated usages. The intermediates M(SΦ)3 are also crystalline and inert against hydrolysis.
- Wada, Masanori,Natsume, Satoko,Suzuki, Shinobu,Uo, Akira,Nakamura, Michiaki,Hayase, Shuichi,Erabi, Tatsuo
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p. 223 - 227
(2007/10/03)
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- An unusual condensation of alkyl 3-oxo-4-(triphenylarsoranylidene)butanoate with aldehydes; synthesis of symmetrical substituted 1,3,5-cycloheptatrienes
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The unique preparation of 2-substituted 4,7-dihydroxycyclohepta-3,5,7-triene-1,3- dicarboxylates 5 from aldehydes 4 and two equivalents alkyl 3-oxo-4-(triphenylarsoranylidene)butanoate 3 is described.
- Moorhoff, Cornelis M.
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p. 4157 - 4160
(2007/10/03)
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- Synthesis and X-ray crystal structure of (p-CH3C6H4)3As=N-S3N3
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A 1:2.5 mole ratio reaction of S4N4 with (p-tolyl)3As in a solvent mixture of CH3CN and C6H6 at ca. 50 deg C gives (p-CH3C6H4)3As=N-S3N3 in ca. 75percent yield after a two day reaction period.The compound, (p-CH3C6H4)3As=N-S3N3 crystallizes in the triclinic space group P with a = 9.216(2) Angstroem, b = 11.124(4) Angstroem, c = 12.398(4) Angstroem, α = 76.43(2) deg, β = 83.06(2) deg, γ = 67.09(2) deg, V = 1137.4(6) Angstroem3, Z = 2.The structure is refined to a final R value of 0.047 with Rw = 0.049.The As-N bond distance is 1.78 Angstroem while the average S-N ring distance is 1.62 Angstroem.Keywords: Arsenic; Tertiary arsines; Thiazenes; X-ray diffraction
- Thomas, C.J.,Cea-Olivares, R.,Espinosa-Perez, G.,Turner, R.W.
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p. 101 - 106
(2007/10/02)
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- Reaction of N-fluoropyridinium salts with Wittig reagents: A novel and convenient approach to symmetric trans-olefins
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N-Fluoropyridinium salts were found to react with Wittig reagents containing electron-withdrawing groups to give olefins in 47-83% yield. The mechanism of this conversion is believed in involve single-electron transfer from Wittig reagent to N-fluoropyridinium cation.
- Kiselyov, Alexander S.
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p. 8951 - 8954
(2007/10/02)
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- ATOM TRANSFER AND EXCHANGE REACTIONS INVOLVING OXYGEN, SULFUR AND SELENIUM
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A systematic comparison has been made of the reaction conditions required to bring about the thermal transfer or exchange of Group 16 terminal elements between Group 15 molecular centers.Where reaction conditions were suitable, kinetic analyses have been performed, with the observed second-order behavior supporting the presumed bimolecular character of these reactions.
- Baechler, Raymond D.,Stack, Mary,Stevenson, Karen,Vanvalkenburgh, Virginia
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- Methyl transfers. 14. Nucleophilic catalysis of nucleophilic substitution
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Nucleophiles X- can catalyze the substitution Nu- + RY → NuR + Y- by adding the faster pathway X- + RY → XR + Y- followed by Nu- + XR → RNu + X-. New examples include catalysis by I- of the exchange of methyl between two dialkyl sulfides and the transfer of methyl from an arsonium salt to a phosphine. The individual reactions are separately studied and some equilibrium information is presented. Iodide is ineffective in the transfer of methyl between two pnosphines, which is not detected with or without iodide. The Marcus equation treatment of this catalysis is shown to require that the identity transfer of R between two X- groups be far faster than that for transfer of R between two Nu- groups. Nucleophiles other than I- are discussed. The possibility that some "supernucleophiles" may have fast identity rates is discussed, and literature evidence that this is indeed the case is presented. Stereochemical studies using chiral methyl derivatives have shown that vitamin B12 does provide a nucleophilic catalysis to methyl transfer in living systems. Thus, the apparently superfluous participation of B12 in some biological methyl transfers is explained.
- McCortney,Jacobson,Vreeke,Lewis
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p. 3554 - 3559
(2007/10/02)
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- PARACYCLOPHANE AS A MODEL FOR THE CONSTRUCTION OF "PERPENDICULAR" STYRENE
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1-Methoxycarbonylmethyleneparacyclophane was synthesized starting from paracyclophane and Ph3As+C-H(CO2CH3).This product is a mixture of Z and E isomers, whose structures and configurations were established by NMR spectroscopy using the nuclear Overhauser effect.
- Kharitonov, V. G.,Nikanorov, V. A.,Mikul'shina, V. V.,Galakhov, M. V.,Oprunenko, Yu. F.,et al.
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p. 1748 - 1750
(2007/10/02)
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- SOME DEOXYGENATION AND REDUCTION REACTIONS WITH SAMARIUM DIIODIDE
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The deoxygenation and reduction of several kinds of organic substrates with samarium diiodide (SmI2) in satisfactory yields are reported.
- Zhang, Yongmin,Lin, Ronghui
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p. 329 - 332
(2007/10/02)
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- Thermodynamic Fitness of Molybdenum(IV, VI) Complexes for Oxygen Atom Transfer Reactions, Including Those with Enzymatic Substrates
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The oxygen (oxo) atom transfer hypothesis for the enzymatic oxidation/reduction of generalized substrate X/XO by the molybdenum oxotransferases (hydroxylases) has been further pursued by an investigation of the reactions of the Mo(VI) and Mo(IV) complexes MoO2(L-NS2) and MoO(L-NS2)(DMF) (L-NS2=2,6-bis(2,2-diphenyl-2-thioethyl)pyridinate(2-)), respectively, in DMF solution.Because of steric hindrance, these molecules execute oxo transfer without formation of a binuclear μ-oxo Mo(V) species.MoO(L-NS2)(DMF) was previously found to reduce quantitatively a variety of sulfoxides, including at least one enzyme substrate.Here this complex is shown to reduce, with formation of MoO2(L-NS2), a series of N-oxides including those of pyridine, nicotinamide, adenine, and tribenzylamine, which are enzyme substrates or pseudosubstrates.Ph3AsO is also reduced by this complex.A previous demonstration of the catalytic partial transfer of 18O in nicotinamide N-oxide to uric acid by xanthine oxidase is interpreted as supporting the oxo transfer hypothesis.MoO2(L-NS2) is reduced by PhSH to MoO(L-NS2)(DMF), further indicating the feasibility of thiols as physiological electron donors.A thermodynamic criterion for the ability of a MoIVO or MoVIO2 complex to reduce or oxidize substrate has been developed on the basis of ΔH values for the reaction X + 1/2O2 -> XO.MoO(L-NS2)(DMF) (21)/MoO2(L-NS2) (22) and MoO(S2CNEt2)2 (20)/MoO2(S2CNEt2)2 (19) are positioned in the reaction series so as to oxidize or reduce (as appropriate) all enzymatic substrates for which thermodynamic data are available.Intermetal oxo transfer reactions of the type MoOLn + MoO2L'n -> MoO2Ln + MoOL'n were investigated with 19-22 and the Schiff base complexes MoO(ssp)(DMF) (18), MoO2(ssp)(DMF) (15), MoO(sap)(DMF) (17), and MoO2(sap)(DMF) (13).These demonstrate the thermodynamic oxo donor order to be S4 (19) > NS2 (22) > ONS (15) > O2N (13); the oxo acceptor order is the reverse.All MoIVO complexes in the set are able to reduce Me2SO to Me2S.This is a necessary but not sufficient thermodynamic criterion for a functional oxo transferase site model.Under the oxo transfer hypothesis, a sufficient model requires access to both the MoIVO and MoVIO2 states at real or effective potentials that can be reached with physiological reductants such that catalysis can be sustained.Evidence is presented that anionic sulfur ligands significantly modulate potentials to values appropriate for catalysis, and that tungsten, having more negative potentials than molybdenum in analogous complexes, is unsuitable for this purpose.
- Harlan, Edgar W.,Berg, Jeremy M.,Holm, R. H.
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p. 6992 - 7000
(2007/10/02)
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- New Reagents, XXXIV. (Diphenylarsino)methyllithium: Synthesis and Preparative Applications
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(Diphenylarsino)methyl iodide (3) was synthesized for the first time (76 percent). (Diphenylarsino)methyllithium (2), stable at 20 deg C, is accessible from 3 (ca. 100 percent) by iodine-lithium exchange with butyl- or phenyllithium and by organoelement-lithium exchange with butyllithium from diphenylarsane (4d; 92 percent). 2, prepared from 4d, gives far better yields of (diphenylarsino)alkanes by the reaction with alkyl halides than 2, obtained from 3.To the contrary, no difference is observed in the reactivity of 2 from 3 or 4d towards aldehydes and ketones.
- Kauffmann, Thomas,Altepeter, Bruno,Klas, Norbert,Kriegesmann, Reinhard
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p. 2353 - 2364
(2007/10/02)
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- TRITOLYLARSONIUM AND TRIS(METHOXYPHENYL)ARSONIUM YLIDES THE EFFECTS OF ortho-SUBSTITUENTS IN TRIARYLARSONIUM GROUPS ON THE PROPERTIES OF YLIDES
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A number of tritolylarsonium and tris(methoxyphenyl)arsonium cyclopentadienylides and other ylides have been prepared and their properties (basicity, NMR spectra, reactions with aldehydes and nitrosobenzene, acetylation, and methanolysis) have been investigated.Substituents in the m- or p-positions of triarylarsonium groups have little effect on properties, but o-substituents result in markedly lower reactivity and lower basicity, and these ylides were also more difficult to prepare.NMR spectra gave indication of crowding in some of these o-substituted ylides.The effects of the o-substituents are discussed. p-Methyl- and p-methoxy-substituents increased the proportion of anil to ketoxime formed in reactions with nitrosobenzene, but the o-methoxy analogue gave only ketoxime.
- Harris, Gordon S.,Lloyd, Douglas,MacDonald, William A.,Gosney, Ian
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p. 297 - 304
(2007/10/02)
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- Phosphides and Arsenides as Metal-Halogen Exchange Reagents. Part 2. Reactions with Aromatic Dihalides
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1,2-Dihalogenobenzenes react with two molar equivalents of lithium diphenylphosphide in the presence of furan to give, after oxidation, triphenylphosphine oxide (major) and the corresponding 2-halogenophenyldiphenylphosphine oxide.No trace of furan-dehydrobenzene adduct was observed in these reactions; however, 1- and 2-naphthyldiphenylphosphine oxides (9:4) were detected.These compounds were the major products from the reaction of the furan-dehydrobenzene adduct with diphenylphosphide, although the ratio of 1- to 2-isomers was quite different (1:9) in this case.Reaction of lithium diphenylphosphide with 3,4-dichloronitrobenzene gave tetrachloroazobenzene (40percent) as the only isolated product and attempts to replace 1,2-dihalogenobenzenes with 2-halogenobenzenediazonium salts gave much lower yields of products.Although dehydrobenzene is thought to be involved in many of these reactions, alternative mechanisms also operate, depending on the halides used.The reaction of lithium diphenylarsenide with 1,2-dihalogenobenzenes gave triphenylarsine as the major product and it seems likely that similar mechanisms to those involved in reactions of diphenylphosphide are operating.Surprisingly, dehydrobenzene-furan adduct reacted with diphenylarsenide to give naphthalene in high yield.
- Gillespie, Donal G.,Walker, Brian J.,Stevens, David,McAuliffe, Charles A.
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p. 1697 - 1703
(2007/10/02)
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- Oxidative Additive Reactions of
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The oxidative addition reactions of the four-coordinated species Ru(NO)Cl(AsPh3)2 (I) with acyl chlorides (RCOCl, R=C6H5, CH3), alkyl and aryl halide, gaseous oxygen, and chlorine, bromine and iodine have been studied.The final products of these reactions are characterised on the basis of elemental analyses and IR spectra.The stereochemistry around the metal is also discussed in some of the cases.The high reactivity of the complex (I) is accounted for in terms of activation due to the presence of the nitrosyl group.Finally a convenient route for the syntheses of mixed ligand complexes of the type Ru(NO)ClX2(AsPh3)L (where X = Br, I; L = base) is suggested.
- Khan, M. Ishaque,Jain, K. C.,Agarwala, U. C.
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- Phosphides and Arsenides as Metal-Halogen Exchange Reagents. Part 1. Dehalogenation of Aliphatic Dihalides
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Lithium diphenylphosphide and arsenide have been investigated as reagents for metal-halogen exchange.Reactions involving two molar equivalents of the anions with 1,2-dibromoethylenes lead to moderate to good yields of acetylenes and smaller yields of phosphorus-containing by-products.Similar reactions with 2,3-dichlorobuta-1,3-diene and 2-chlorobuta-1,3-diene give SN2' rather than direct substitution products.Evidence is presented that adamantene is an initial product in the reaction of lithium diphenylphosphide with 1,2-di-iodo- and 1,2-dibromo-adamantane, but not with 1,2-dichloroadamantane, although 1- and 2-adamantyldiphenylphosphine oxides are formed in every case.Finally reactions of phosphide anion with geminal dihalides were briefly investigated; 1,1-dibromo-2,2-diphenylethylene gave diphenylacetylene as the major product.
- Gillespie, Donal G.,Walker, Brian J.
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p. 1689 - 1695
(2007/10/02)
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- Photostimulated Reaction of Diphenylarsenide and Diphenylstibide Ions with Haloaromatic Compounds by the SRN1 Mechanism. Electron Transfer vs. Bond Breaking of the Radical Anion Intermediate
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Photostimulated reactions of haloaromatic compounds with potassium diphenylarsenide and potassium diphenylstibide were studied in liquid ammonia. 1-Bromonaphthalene and 9-bromophenanthrene reacted with diphenylarsenide ion to give four products: triphenylarsine, diphenylarylarsine, phenyldiarylarsine, and triarylarsine (aryl = 1-naphthyl and 9-phenanthryl); with 2-chloroquinoline as substrate only the straightforward substitution product 2-qiunolyldiphenylarsine was formed. p-Bromoanisole and 4-chlorobenzophenone reacted with potassium diphenylstibide to give four stibines: triphenylstibine, diphenylarylstibine, phenyldiarylstibine, and triarylstibine (aryl = p-anisyl and 4-benzoylphenyl).These reactions are believed to occur by the SRN1 mechanism with an extra feature of reversible coupling of aryl radicals with arsenide and stibide ions, which causes the scrambling of aryl rings.It is suggested that the low-lying ?* MO of the quinolyl moiety prevents C-As bond breaking of the radical anion intermediate.
- Alonso, Ruben A.,Rossi, Roberto A.
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- Oxotrihalogenoselenates(IV): Preparation, Structure and Properties of P(C6H5)4SeOCl3, P(C6H5)4SeOBr3 and As(C6H5)4SeOBr3
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The novel oxotribromoselenate(IV) SeOBr3(-) anion was prepared from the reaction of stoichiometric quantities of SeOBr2 and bromide in acetonitrile solution, and it was isolated as the tetraphenylphosphonium and -arsonium salts in crystalline form.For the synthesis of the analogous SeOCl3(-) as P(C6H5)4SeOCl3, SeCl4 was reacted in the presence of a small quantity of H2O with P(C6H5)4Cl in acetonitrile.Complete X-ray structural analyses of P(C6H5)4SeOCl3 (space group P, a = 10.981(3), b = 11.059(3), c = 10.358(3) Angstroem, α = 73.77(2) deg, β = 83.33(2) deg, γ = 80.51(2) deg, V = 1187.9(6) Angstroem3) and of P(C6H5)4SeOBr3 (space group P21/c, a = 11.719(4), b = 16.088(4), c = 13.124(4) Angstroem, β = 94.72(3) deg, V = 2466(1) Angstroem3) show dimeric centrosymmetric Se2O2Cl6(2-) and Se2O2Br6(2-) anions being present in the solid.In the anions two square-pyramidal (ψ-octahedral) SeOHal4 groups are connected through a common Hal-Hal edge.The axial oxygen ligands (Se-O: 1.597(4) and 1.584(6) Angstroem) cause a pronounced sterochemical trans-activation of the inert pairs at the Se atoms.As(C6H5)4SeOBr3 is isotypic with P(C6H5)4SeOCl3. - Key words: Oxohalogenoselenate, Crystal Structure, Selenium
- Krebs, Bernt,Schaeffer, Andreas,Hucke, Marita
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p. 1410 - 1417
(2007/10/02)
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- Photostimulated Reactions of Potassium Diphenylarsenide with Haloarenes by the SRN1 Mechanism
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Photostimulated reactions of haloarenes with potassium diphenylarsenide (3) were studied in liquid ammonia. p-Chloro-, p-bromo-, and p-iodotoluenes gave four products: triphenylarsine, p-tolyldiphenylarsine, di-p-tolylphenylarsine and tri-p-tolylarsine.Similarly, with p-chloro, p-bromo-, and p-iodoanisole as substrates, four arsines were found as products: triphenylarsine, p-anisyldiphenylarsine, di-p-anisylphenylarsine and tri-p-anisylarsine. p-Chlorotoluene and p-bromoanisole are unreactive in the dark, but with 4-chlorobenzophenone there is a dark reaction, which is accelerated by light and inhibited by m-dinitrobenzene and oxygen.Withthe latter substrate, only the straightforward substitution product is formed.These reactions are believed to occur by the SRN1 mechanism, with an exstra feature of reversible coupling of aryl radicals with arside ions, which causes the scrambling of aryl rings.It is suggested that the low-lying ?* MO of the benzophenone moiety prevents C-As bond breaking in the radical anion intermediate in that case.
- Rossi, Roberto A.,Alonso, Ruben A.,Palacios, Sara M.
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p. 2498 - 2502
(2007/10/02)
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- LIGAND DISSOCIATION FROM MONO-SUBSTITUTED DERIVATIVES OF HEXACARBONYLCHROMIUM (Cr(CO)5L, L = P(C6H5)3, P(C4H9)3, P(OCH3)3, P(OC6H5)3, AND As(C6H5)3)
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The rates of dissociation of the unique ligand from Cr(CO)5L have been determined for L = P(C6H5)3, P(OC6H5)3, P(OCH3)3, and As(C6H5)3 by reaction with CO.The reactions were investigated from 80-140 deg C and activation parameters were determined.The rate
- Wovkulich, Michael J.,Atwood, Jim D.
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- Selective formation of ethanol from methanol, hydrogen and carbon monoxide
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A process for the selective formation of ethanol which comprises contacting methanol, hydrogen and carbon monoxide with a catalyst system comprising cobalt acetylacetonate, a tertiary organo Group V A compound of the periodic Table, a first promoter comprising an iodine compound and a second promoter comprising a ruthenium compound.
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- Structural studies of derivatives of methinyltricobalt enneacarbonyls. I. The crystal structure of CH3CCo3(CO)8P(C6H5) 3
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The crystal and molecular structure of CH3CCo3(CO)8P(C6H5) 3 has been determined by three-dimensional X-ray analysis. Crystals of the compound are monoclinic, space group C2h5-P21/c, with four molecules in a cell of dimensions a = 12.19 (2), b = 16.11 (2), c = 17.19 (4) ?; β = 120.0 (1)°. X-Ray data were collected by conventional film techniques using Co Kα radiation, the intensities of 2189 independent reflections being measured photometrically. The structure has been refined isotropically by modified full-matrix least-squares techniques to a conventional R factor of 0.099. The monomeric molecular structure closely resembles the parent compound CH3CCo3(CO)9 being based on a Co3 triangle. The P(C6H5)3 unit has simply replaced one of the equatorial carbonyl groups, causing small distortions in the remainder of the molecule. Co-Co bond lengths are in the range 2.490-2.510 (6) ?.
- Brice,Penfold,Robinson, Ward T.,Taylor, Susan R.
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p. 362 - 367
(2008/10/08)
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