- Conversion from Heterometallic to Homometallic Metal–Organic Frameworks
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Two new heterometallic metal–organic frameworks (MOFs), LnZnTPO 1 and 2, and two homometallic MOFs, LnTPO 3 and 4 (Ln=Eu for 1 and 3, and Tb for 2 and 4; H3TPO=tris(4-carboxyphenyl)phosphine oxide) were synthesized, and their structures and pro
- Song, Jeong Hwa,Lee, Giseong,Yoon, Jung Heum,Jang, Junyeon,Choi, Doosan,Yun, Heejun,Kwon, Kangin,Kim, Hojin,Hong, Chang Seop,Kim, Youngki,Han, Hogyu,Lim, Kwang Soo,Lee, Woo Ram
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Read Online
- N-heterocyclic carbene complexes of palladium in oxygen atom transfer reactions involving the making and breaking of N-O bonds
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Reaction of three equivalents of MesCNO (Mes = 2,4,6-trimethylphenyl) with one equivalent of [Pd(IPr)(P(p-tolyl)3)] in toluene yields the solid complex [Pd(IPr)(NCMes)(κ2-O–N[dbnd]C-Mes(–N–C([dbnd]O)Mes))]. Three major steps are proposed to be involved in the reaction based on spectroscopic studies as well as literature precedents for related cycloadditions: i. oxidation of the coordinated phosphine ligand to phosphine oxide ii. oxygen atom transfer forming a C[dbnd]O bond from the N–O bond of MesCNO, and iii. cycloaddition of a final MesCNO ligand to yield product. Addition of two equivalents of [rad]NO at low temperature to the in situ generated peroxide complex [Pd(IPr)2(η2-O2)] generates the N-bonded complex trans-[Pd(IPr)2(NO2)2] in keeping with a literature precedent reported for similar complexes. Insight into the energetics of this reaction are probed by DFT calculations using the truncated ligand complex [Pd(IMe)2]. The computed enthalpy of binding of two moles of [rad]NO2 to form [Pd(IMe)2(NO2)2] is ?112 kcal/mol indicating that its preparation from [Pd(IMe)2], N2 and 2O2 is thermodynamically favorable by ?96 kcal/mol. Crystal structures of [Pd(IPr)(NCMes)(κ2-O–N[dbnd]C-Mes(–N–C([dbnd]O)Mes))] and trans-[Pd(IPr)2(NO2)2] are reported.
- Cai, Xiaochen,Majumdar, Subhojit,Serafim, Leonardo F.,Temprado, Manuel,Nolan, Steven P.,Cazin, Catherine S.J.,Captain, Burjor,Hoff, Carl D.
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- Palladium-Catalyzed C-P Bond-Forming Reactions of Aryl Nonaflates Accelerated by Iodide
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An iodide-accelerated, palladium-catalyzed C-P bond-forming reaction of aryl nonaflates is described. The protocol was optimized for the synthesis of aryl phosphine oxides and was found to be tolerant of a wide range of aryl nonaflates. The general nature of this transformation was established with coupling to other P(O)H compounds for the synthesis of aryl phosphonates and an aryl phosphinate. The straightforward synthesis of stable, isolable aryl nonaflates, in combination with the rapid C-P bond-forming reaction allows facile preparation of aryl phosphorus target compounds from readily available phenol starting materials. The synthetic utility of this general strategy was demonstrated with the efficient preparation of an organic light-emitting diode (OLED) material and a phosphonophenylalanine mimic.
- McErlain, Holly,Riley, Leanne M.,Sutherland, Andrew
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p. 17036 - 17049
(2021/11/18)
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- A Mononuclear Non-Heme Manganese(III)-Aqua Complex in Oxygen Atom Transfer Reactions via Electron Transfer
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Metal-oxygen complexes, such as metal-oxo [M(O2-)], -hydroxo [M(OH-)], -peroxo [M(O22-)], -hydroperoxo [M(OOH-)], and -superoxo [M(O2?-)] species, are capable of conducting oxygen atom transfer (OAT) reactions with organic substrates, such as thioanisole (PhSMe) and triphenylphosphine (Ph3P). However, OAT of metal-aqua complexes, [M(OH2)]n+, has yet to be reported. We report herein OAT of a mononuclear non-heme Mn(III)-aqua complex, [(dpaq)MnIII(OH2)]2+ (1, dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate), to PhSMe and Ph3P derivatives for the first time; it is noted that no OAT occurs from the corresponding Mn(III)-hydroxo complex, [(dpaq)MnIII(OH)]+ (2), to the substrates. Mechanistic studies reveal that OAT reaction of 1 occurs via electron transfer from 4-methoxythioanisole to 1 to produce the 4-methoxythioanisole radical cation and [(dpaq)MnII(OH2)]+, followed by nucleophilic attack of H2O in [(dpaq)MnII(OH2)]+ to the 4-methoxythioanisole radical cation to produce an OH adduct radical, 2,4-(MeO)2C6H3S?(OH)Me, which disproportionates or undergoes electron transfer to 1 to yield methyl 4-methoxyphenyl sulfoxide. Formation of the thioanisole radical cation derivatives is detected by the stopped-flow transient absorption measurements in OAT from 1 to 2,4-dimethoxythioanisole and 3,4-dimethoxythioanisole, being compared with that in the photoinduced electron transfer oxidation of PhSMe derivatives, which are detected by laser-induced transient absorption measurements. Similarly, OAT from 1 to Ph3P occurs via electron transfer from Ph3P to 1, and the proton effect on the reaction rate has been discussed. The rate constants of electron transfer from electron donors, including PhSMe and Ph3P derivatives, to 1 are fitted well by the electron transfer driving force dependence of the rate constants predicted by the Marcus theory of outer-sphere electron transfer.
- Sharma, Namita,Zou, Huai-Bo,Lee, Yong-Min,Fukuzumi, Shunichi,Nam, Wonwoo
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p. 1521 - 1528
(2021/02/01)
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- Microwave assisted P–C coupling reactions without directly added P-ligands
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Our group introduced a green protocol for the Pd(OAc)2- or NiCl2-catalyzed P–C coupling reaction of aryl halides and various > P(O)H-compounds under MW conditions without directly added P-ligands. The reactivity of a few aryl derivatives in the Pd(OAc)2-catalyzed Hirao reaction was also studied. An induction period was observed in the reaction of bromobenzene and diphenylphosphine oxide. Finally, the less known copper(I)-promoted P–C coupling reactions were investigated experimentally. The mechanism was explored by quantum chemical calculations.
- Henyecz, Réka,Huszár, Bianka,Keglevich, Gy?rgy,Mucsi, Zoltán
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- Synthesis of Azaylide-Based Amphiphiles by the Staudinger Reaction
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Catalyst- and reagent-free reactions are powerful tools creating various functional molecules and materials. However, such chemical bonds are usually hydrolysable or require specific functional groups, which limits their use in aqueous media. Herein, we report the development of new amphiphiles through the Staudinger reaction. Simple mixing of chlorinated aryl azide with a hydrophilic moiety and various triarylphosphines (PAr3) gave rise to azaylide-based amphiphiles NPAr3, rapidly and quantitatively. The obtained NPAr3 formed ca. 2 nm-sized spherical aggregates (NPAr3)n in water. The hydrolysis of NPAr3 was significantly suppressed as compared with those of non-chlorinated amphiphiles nNPAr3. Computational studies revealed that the stability is mainly governed by the decrease in LUMO around the phosphorus atom owing to the o-substituted halogen groups. Furthermore, hydrophobic dyes such as Nile red and BODIPY were encapsulated by the spherical aggregates (NPAr3)n in water.
- Kishida, Natsuki,Suzuki, Hayate,Toyota, Shinji,Yamashina, Masahiro,Yoshizawa, Michito
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supporting information
p. 17915 - 17919
(2021/07/09)
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- One-pot cascade ring enlargement of isatin-3-oximes to 2,4-dichloroquinazolines mediated by bis(trichloromethyl)carbonate and triarylphosphine oxide
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An efficient and convenient one-pot cascade synthesis of 2,4-dichloroquinazolines directly from isatin-3-oximes with the addition of bis(trichloromethyl)carbonate and triarylphosphine oxide was developed, leading to substituted quinazolines in moderate to excellent yields. The efficiency of this transformation was demonstrated by compatibility with a range of functional groups. Thus, the method represents a convenient and practical strategy for the synthesis of substituted 2,4-dichloroquinazolines.
- Qin, Jinjing,Li, Zhenhua,Ma, Shengzhe,Ye, Lixian,Jin, Guoqiang,Su, Weike
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supporting information
p. 1007 - 1012
(2020/07/10)
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- Di(hydroperoxy)cycloalkane Adducts of Triarylphosphine Oxides: A Comprehensive Study including Solid-State Structures and Association in Solution
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Four new di(hydroperoxy)cycloalkane adducts (Ahn adducts) of p-Tol3PO (1) and o-Tol3PO (2), namely, p-Tol3PO·(HOO)2C(CH2)5 (3), o-Tol3PO·(HOO)2C(CH2)5 (4), p-Tol3PO·(HOO)2C(CH2)6 (5), and o-Tol3PO·(HOO)2C(CH2)6 (6), have been synthesized and fully characterized. Their single crystal X-ray structures have been determined and analyzed. The 31P NMR data are in accordance with hydrogen bonding of the di(hydroperoxy)alkanes to the P═O groups of the phosphine oxides. Due to their high solubility in organic solvents, natural abundance 17O NMR spectra of 1-6 could be recorded, providing the signals for the P═O groups and additionally the two different oxygen nuclei in the O-OH groups in the adducts 3-6. The association and mobility of 3-6 were explored by 1H DOSY (diffusion ordered spectroscopy) NMR, which indicated persistent hydrogen bonding of the adducts in solution. Competition experiments with phosphine oxides allowed ranking of the affinities of the di(hydroperoxy)cycloalkanes for the different phosphine oxide carriers. On the basis of variable temperature 31P NMR investigations, the Gibbs energies of activation ΔG? for the adduct dissociation processes of 3-6 at different temperatures, as well as the enthalpy ΔH? and entropy ΔS? of activation, have been determined. IR spectroscopy of 3-6 corroborated the hydrogen bonding, and in the Raman spectra, the ν(O-O) stretching bands have been identified, confirming the presence of peroxy groups in the solid materials. The high solubilities in selected organic solvents have been quantified.
- Arp, Fabian F.,Bhuvanesh, Nattamai,Blümel, Janet
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p. 13719 - 13732
(2020/10/02)
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- Photooxidation of triarylphosphines under aerobic conditions in the presence of a gold(iii) complex on cellulose extracted from Carthamus tinctorius immobilized on nanofibrous phosphosilicate
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Triarylphosphines were converted to the corresponding oxides via photooxidation as a novel method. In this study, cellulose was extracted from the Carthamus tinctorius plant and then oxidized by sodium metaperiodate. A gold complex was supported on this natural cellulose. Then, a gold complex on natural cellulose supported on FPS (FPS/Au(iii)) was synthesized for the reduction of phosphine oxides to corresponding phosphines with remarkable chemoselectivity. The morphology of FPS led to higher catalytic activity. FPS/Au(iii) NPs were thoroughly characterized using TEM, FESEM, FTIR, TGA, and BET.
- Sadeghzadeh, Seyed Mohsen,Zhiani, Rahele
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p. 1509 - 1516
(2019/01/24)
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- Visible light-induced 4-phenylthioxanthone-catalyzed aerobic oxidation of triarylphosphines
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We report herein a visible light-induced oxidation of triarylphosphines under aerobic condition with excellent functional group tolerance. In this transformation, the photo catalyst 4-phenylthioxanthone acted as a photosensitizer for the in situ generation of singlet oxygen. This new approach provided a cheaper and greener method for the preparation of phosphine oxide, showing great advantages in environmental protocols.
- Ding, Aishun,Li, Shijie,Chen, Yang,Jin, Ruiwen,Ye, Cong,Hu, Jianhua,Guo, Hao
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supporting information
p. 3880 - 3883
(2018/09/27)
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- Electrophilic Phosphonium Cation-Mediated Phosphane Oxide Reduction Using Oxalyl Chloride and Hydrogen
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The metal-free reduction of phosphane oxides with molecular hydrogen (H2) using oxalyl chloride as activating agent was achieved. Quantum-mechanical investigations support the heterolytic splitting of H2 by the in situ formed electrophilic phosphonium cation (EPC) and phosphane oxide and subsequent barrierless conversion to the phosphane and HCl. The reaction can also be catalyzed by the frustrated Lewis pair (FLP) consisting of B(2,6-F2C6H3)3 and 2,6-lutidine or phosphane oxide as Lewis base. This novel reduction was demonstrated for triaryl and diaryl phosphane oxides providing access to phosphanes in good to excellent yields (51–93 %).
- Stepen, Arne J.,Bursch, Markus,Grimme, Stefan,Stephan, Douglas W.,Paradies, Jan
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supporting information
p. 15253 - 15256
(2018/10/24)
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- Interception of intermediates in phosphine oxidation by mesityl nitrile-: N -oxide using frustrated Lewis pairs
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Phosphine oxidation by MesCNO is rapid; however, an FLP strategy intercepts the 1,3 addition products including [MesC(R3P)NOB(C6F5)3] (R = Ph 1, p-tol 2), [MesC(Mes2PH)NOB(C6F5)3] 3 (MesC(NOB(C6F5)3)Ph2P)2(CH2)n (n = 2: 4, 3: 5) and [MesC(Ph3P)NOB(C6F4H)3] 6. These species are shown to react with tBuOK or [Bu4N]F permitting the oxidation to proceed via a process involving borane dissociation. Similarly, the equilibrium established by 1 with B(C6F4H)3 and 6 with B(C6F5)3 provides experimental support for the "Cummins mechanism" for these phosphine oxidations.
- Szkop, Kevin M.,Zhu, Diya,Longobardi, Lauren E.,Heck, Julian,Stephan, Douglas W.
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supporting information
p. 8933 - 8939
(2018/07/25)
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- Phosphine Oxidation with Water and Ferrocenium(III) Cation Induced by Visible-Light Irradiation
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Stoichiometric oxidation of phosphines with water and ferrocenium(III) cation as the oxygen atom source and the oxidizing reagent, respectively, was achieved in acetonitrile under visible-light irradiation by using 2,6-lutidine as the proton acceptor. The reaction required light irradiation, under which fluorescence was observed for the acetonitrile solution of the ferrocenium(III) cation.
- Tanabe, Yoshiaki,Nakajima, Kazunari,Nishibayashi, Yoshiaki
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supporting information
p. 18618 - 18622
(2018/11/30)
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- A new method to prepare functional phosphines through steady-state photolysis of triarylphosphines
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The steady-state photolysis of triarylphosphine, Ar3P, was carried out using a xenon lamp or a high-pressure mercury lamp under an argon atmosphere in a solvent containing a functional group, CH3X. Gas chromatograph-mass spectroscopic analysis on the photolysis showed that a phosphine to which the functional group from the solvent is incorporated, Ar2PCH2X, was formed in a moderate yield, along with tetraaryldiphosphine, Ar2PPAr2. The product, Ar2PCH2CN, from the photolysis in acetonitrile (X=CN) was isolated by column chromatography. In the photolysis in other solvents tried here (ethyl acetate, acetone, 2-butanone, and 3,3-dimethyl-2-butanone), Ar2PCH2X formed in the reaction mixture was so labile on a silica-gel column that it was treated with S8 powder to convert to the corresponding phosphine sulfide, Ar2P(=S)CH2X. The resulting phosphine sulfide was isolated by column chromatography. The isolated products in these reactions, Ar2PCH2CN and Ar2P(=S)CH2X, were characterized by 1H, 13C, and 31P NMR spectroscopy, IR spectroscopy, and elemental analysis or high-resolution mass spectroscopy. The formation of Ar2PCH2X as well as Ar2PPAr2 is explained by homolytic cleavage of a P-C bond of Ar3P in the photoexcited state. This reactivity of Ar3P in the photoexcited state is in sharp contrast to that exerted under aerobic conditions, where Ar3P in the photoexcited state donates readily an electron to oxygen producing the radical cation, Ar3P·+. This photoreaction, which affords a functional phosphine, Ar2PCH2X, in one-pot with generating very small amounts of unidentified side products, has potential for use in preparing functional phosphines.
- Yasui, Shinro,Ando, Taro,Ozaki, Masashi,Ogawa, Yuya,Shioji, Kosei
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- Enhanced Luminescence of Asymmetrical Seven-Coordinate EuIII Complexes Including LMCT Perturbation
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Luminescent mononuclear seven-coordinate EuIII complexes, with monocapped-octahedral (point group: C3v), monocapped-trigonal-prismatic (C2v), and pentagonal-bipyramidal (D5h) coordination structures, are reporte
- Yanagisawa, Kei,Kitagawa, Yuichi,Nakanishi, Takayuki,Akama, Tomoko,Kobayashi, Masato,Seki, Tomohiro,Fushimi, Koji,Ito, Hajime,Taketsugu, Tetsuya,Hasegawa, Yasuchika
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p. 3843 - 3848
(2017/09/07)
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- Eosin Y-catalyzed photooxidation of triarylphosphines under visible light irradiation and aerobic conditions
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We report herein a novel method for Eosin Y-catalyzed photooxidation of triarylphosphines under visible light irradiation and aerobic conditions. This new approach employed visible light as the energy source and air as the oxidant, showing great advantages in environmental benignness and operational easiness with a wide functional group tolerance.
- Zhang, Yanbin,Ye, Cong,Li, Shijie,Ding, Aishun,Gu, Guangxin,Guo, Hao
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p. 13240 - 13243
(2017/03/09)
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- Direct oxygen atom transfer versus electron transfer mechanisms in the phosphine oxidation by nonheme Mn(IV)-oxo complexes
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Direct oxygen atom transfer from a nonheme Mn(iv)-oxo complex, [(Bn-TPEN)MnIV(O)]2+, to triphenylphosphine (Ph3P) derivatives occurs with a significant steric effect resulting from the ortho-substituents on the phenyl group of the Ph3P derivatives, whereas the phosphine oxygenation by a Mn(iv)-oxo complex in the presence of HOTf occurs via an electron transfer mechanism without the substrate-steric effect.
- Lee, Yong-Min,Yoo, Mi,Yoon, Heejung,Li, Xiao-Xi,Nam, Wonwoo,Fukuzumi, Shunichi
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supporting information
p. 9352 - 9355
(2017/08/23)
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- New reactions and reactive intermediates in the pyrolysis of cyclic phosphonium ylides
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Pyrolysis, either neat or in diphenyl ether solution, results in the conversion of both 4-triphenylphosphoranylidenetetrahydrofuran-2,3,5-trione and 4-triphenylphosphoranylidenetetrahydrothio-phene-2,3,5-trione into 3,5-bis(triphenylphosphoranylidene)cyclopentane-1,2,4-trione. These reactions involve extrusion of CO2 or COS to give 3-triphenylphosphoranylidenecyclopropane-1,2-dione which further loses CO to give triphenylphosphoranylideneketene. The precise way in which these two reactive phosphorus compounds combine to give the observed product has been examined by chemical and isotopic labelling studies. Cyclotrimerization of triphenylphosphoranylideneketene upon thermolysis in diphenyl ether has also been observed for the first time. The erroneous literature interpretation of the 13C NMR spectrum for triphenylphosphoranylideneketene is corrected.
- Aitken, R. Alan,Bj?rnstad, Vidar,Massil, Tracy,Skramstad, Jan,Young, Robert J.
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p. 293 - 301
(2017/10/27)
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- Novel metallo-therapeutics of the NSAID naproxen. Interaction with intracellular components that leads the cells to apoptosis
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Two new mixed ligand-silver(i) complexes of the anti-inflammatory drug naproxen (naprH) and triphenylphosphine (tpp) or tri(p-tolyl)phosphine (tptp) of formulae {[Ag(tpp)3(napr)](H2O)} (1) and [Ag(tptp) 2(napr)] (2) have b
- Banti,Giannoulis,Kourkoumelis,Owczarzak,Kubicki,Hadjikakou
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p. 6848 - 6863
(2014/05/06)
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- Iridium(III)-Catalyzed C H Amidation of Arylphosphoryls Leading to a P-Stereogenic Center
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Direct C H amidation of arylphosphoryl compounds has been developed by using an IrIIIcatalyst system under mild conditions. A wide range of substrates could be employed with high functional-group tolerance. This procedure was successfully applied for the first time to the asymmetric reaction giving rise to a P-chirogenic center with a high diastereomeric ratio of up to 19:1 (90 % de).
- Gwon, Donghyeon,Lee, Donggun,Kim, Jiyu,Park, Sehoon,Chang, Sukbok
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supporting information
p. 12421 - 12425
(2016/08/25)
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- HETEREOCYCLIC AGENT AS CATALYTIC STABILIZING AGENT IN A HYDROFORMYLATION PROCESS
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A heterocyclic nitrogen stabilizing agent is employed to reduce the rate of catalyst deactivation in a hydroformylation process.
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Page/Page column 35
(2014/10/03)
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- Redox properties of a mononuclear copper(II)-superoxide complex
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Redox properties of a mononuclear copper(II) superoxide complex, (L)Cu II-OO?, supported by a tridentate ligand (L = 1-(2-phenethyl)-5-[2-(2-pyridyl)ethyl]-1,5-diazacyclooctane) have been examined as a model compound of the putative reactive intermediate of peptidylglycine α-hydroxylating monooxygenase (PHM) and dopamine β-monooxygenase (DβM) (Kunishita et al. J. Am. Chem. Soc. 2009, 131, 2788-2789; Inorg. Chem. 2012, 51, 9465-9480). On the basis of the reactivity toward a series of one-electron reductants, the reduction potential of (L)CuII-OO ? was estimated to be 0.19 ± 0.07 V vs SCE in acetone at 298 K (cf. Tahsini et al. Chem. - Eur. J. 2012, 18, 1084-1093). In the reaction of TEMPO-H (2,2,6,6-tetramethylpiperidine-N-hydroxide), a simple HAT (hydrogen atom transfer) reaction took place to give the corresponding hydroperoxide complex LCuII-OOH, whereas the reaction with phenol derivatives (XArOH) gave the corresponding phenolate adducts, LCu II-OXAr, presumably via an acid-base reaction between the superoxide ligand and the phenols. The reaction of (L)CuII-OO ? with a series of triphenylphosphine derivatives gave the corresponding triphenylphosphine oxides via an electrophilic ionic substitution mechanism with a Hammett ρ value as -4.3, whereas the reaction with thioanisole (sulfide) only gave a copper(I) complex. These reactivities of (L)CuII-OO? are different from those of a similar end-on superoxide copper(II) complex supported by a tetradentate TMG 3tren ligand (1,1,1-Tris{2-[N2-(1,1,3,3- tetramethylguanidino)]ethyl}amine (Maiti et al. Angew. Chem., Int. Ed. 2008, 47, 82-85).
- Tano, Tetsuro,Okubo, Yuri,Kunishita, Atsushi,Kubo, Minoru,Sugimoto, Hideki,Fujieda, Nobutaka,Ogura, Takashi,Itoh, Shinobu
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p. 10431 - 10437
(2013/10/01)
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- Effect of ligand polarization on asymmetric structural formation for strongly luminescent lanthanide complexes
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The effect of ligand polarization on the formation of strongly luminescent lanthanide complexes with asymmetric structures is described for the first time. The lanthanide complexes are composed of EuIII ions, three hexafluoroacetylacetonate (hfa) ligands, and two monodentate phosphine oxide ligands, namely, triphenylphosphine oxide (TPPO), p-tolyldiphenylphosphine oxide (TPPO-Me), tri-p-tolylphosphine oxide (TPPO-3Me) or o- phenoxyphenyldiphenylphosphine oxide (TPPO-OPh). The luminescence properties of the EuIII complexes are characterized by their emission quantum yields, emission lifetimes, and their radiative (kr) and nonradiative (knr) rate constants. The EuIII complex with TPPO-OPh ligands offers a markedly high emission quantum yield (72 % in [D 6]acetone, 85 % in the solid state) owing to enhancement of the electric dipole transition and suppression of vibrational relaxation, which are directly related to kr and knr. The coordination geometries of the EuIII complexes are categorized by shape-measure calculations. The EuIII complexes exhibit characteristic square-antiprismatic or trigonal-dodecahedral structures, depending on the ligand polarization. Strongly luminescent Eu(hfa)3(TPPO-OPh) 2 has an asymmetric dodecahedron structure. The formation of distorted dodecahedral structures with low vibrational frequencies for the enhancement of luminescence is elucidated in terms of the ligand polarization of the monodentate phosphine oxide ligands in the EuIII complexes. EuIII complexes with three hexafluoroacetylacetonate and two monodentate phosphine oxide ligands exhibit characteristic square-antiprismatic or trigonal-dodecahedral structures depending on the ligand polarization. Ligands with large dipole moments result in characteristic dodecahedron structures and markedly high emission quantum yields (72 % in [D 6]acetone, 85 % in the solid state).
- Hasegawa, Yasuchika,Ohkubo, Tomoki,Nakanishi, Takayuki,Kobayashi, Atsushi,Kato, Masako,Seki, Tomohiro,Ito, Hajime,Fushimi, Koji
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p. 5911 - 5918
(2013/12/04)
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- Ruthenium-catalyzed ortho -alkenylation of phenylphosphine oxides through regio- and stereoselective alkyne insertion into C-H bonds
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Direct ortho-substitution took place efficiently upon treatment of tri-, di-, and monoarylphosphine oxides with internal alkynes in the presence of a ruthenium catalyst to produce (o-alkenylphenyl)phosphine oxides regio- and stereoselectively. Chemoselective reduction of a product gave the corresponding (o-alkenylphenyl)phosphine, which may be useful as a ligand for transition metals.
- Itoh, Masaki,Hashimoto, Yuto,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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p. 8098 - 8104
(2013/09/12)
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- Investigation of non-Rehm-Weller kinetics in the electron transfer from trivalent phosphorus compounds to singlet excited sensitizers
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Singlet excited states (1S* and 1S +*) of neutral and monocationic sensitizers, S and S +, respectively, were quenched by electron transfer (ET) from a variety of trivalent phosphorus compounds (Z3P). The quenching rate constants kq, which are equal to the rate constants kET of the ET from Z3P to 1S* or 1S+*, were determined by the Stern-Volmer method. The logarithm of kET was plotted against free-energy change ΔG0 of the ET. The plot deviated upward from the line predicted by the Rehm-Weller (RW) theory in the endothermic region, the deviation being larger in the ET to a neutral acceptor 1S* than in the ET to a cationic acceptor 1S+*. Such a kinetic behavior is in sharp contrast to that observed in the ET from amines (R 3N), where the ET to either neutral or cationic acceptor takes place according to the RW prediction. The ET from a donor, Z3P or R 3N, to a neutral acceptor 1S* is a charge-separation type, during which electrostatic attraction between the donor and the acceptor is generated, whereas the ET to a cationic acceptor 1S+* is a charge-shift type, which results in neither electrostatic attraction nor repulsion. Difference in kinetics-energetics relationship by the type of ET, which is not recognized in the ET from R3N donor, becomes "visible" when Z 3P is used as a donor. Copyright 2013 John Wiley & Sons, Ltd. The rate constants kET of electron transfer from trivalent phosphorus compounds to singlet photoexcited sensitizers were determined by the Stern-Volmer method. LogkET-ΔG0 plots were found to deviate upward from the line predicted by the Rehm-Weller theory, with deviation being larger in ET to neutral acceptors than in ET to cationic acceptors. Copyright
- Yasui, Shinro,Tsujimoto, Munekazu
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p. 1090 - 1097
(2014/01/06)
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- Remarkably robust monomeric alkylperoxyzinc compounds from tris(oxazolinyl)boratozinc alkyls and O2
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Metal alkylperoxides are remarkable, highly effective, yet often thermally unstable, oxidants that may react through a number of possible pathways including O-O homolytic cleavage, M-O homolytic cleavage, nucleophilic O-atom transfer, and electrophilic O-atom transfer. Here we describe a series of zinc alkyl compounds of the type ToMZnR (ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate; R = Et, n-C3H 7, i-C3H7, t-Bu) that react with O2 at 25 °C to form isolable monomeric alkylperoxides ToMZnOOR in quantitative yield. The series of zinc alkylperoxides is crystallographically characterized, and the structures show systematic variations in the Zn-O-O angle and O-O distances. The observed rate law for the reaction of ToMZnEt (2) and O2 is consistent with a radical chain mechanism, where the rate-limiting SH2 step involves the interaction of ?OOR and ToMZnR. In contrast, ToMZnH and ToMZnMe are unchanged even to 120 °C under 100 psi of O 2 and in the presence of active radical chains (e.g., ?OOEt). This class of zinc alkylperoxides is unusually thermally robust, in that the compounds are unchanged after heating at 120 °C in solution for several days. Yet, these compounds are reactive as oxidants with phosphines. Additionally, an unusual alkylperoxy group transfer to organosilanes affords ToMZnH and ROOSiR3'.
- Mukherjee, Debabrata,Ellern, Arkady,Sadow, Aaron D.
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supporting information; scheme or table
p. 13018 - 13026
(2012/10/08)
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- Mechanistic study on photooxidation of triarylphosphines by time-resolved infrared spectroscopy
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Upon laser flash photolysis on a solution of triarylphosphine Ar 3P in acetonitrile or dichloromethane using a YAG laser at 266 nm, transient absorption was observed by time-resolved infrared spectroscopy. Rate constants were determined for the formation step of the absorption. Dependency of the rate on [Ar3P] and atmosphere, along with independent observation in laser flash photolysis/UV-Vis spectroscopy of the Ar3P solutions, suggeststhat electron transfer occurs from Ar3P to the singlet photoexcited state of Ar3P, generating triarylphosphine radical cation Ar3P .+, which reacts with a trace amount of H2O in the solvent to give the final product Ar3P O, which has been observed in steady-state photolysis. Copyright Taylor & Francis Group, LLC.
- Yasui, Shinro,Mishima, Masaaki
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experimental part
p. 838 - 840
(2011/06/25)
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- N,N-Dimethyl-S-difluoromethyl-S-phenylsulfoximinium tetrafluoroborate: A versatile electrophilic difluoromethylating reagent
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Over the past decade, sulfur-based fluoromethyl containing compounds have been exhaustively investigated as versatile fluoroalkylating reagents by our research laboratory as well as many others. Lately, we have designed a novel electrophilic difluoromethylating protocol employing in situ prepared N,N-dimethyl-S-difluoromethyl-S-phenylsulfoximinium salt. The present reagent provides excellent reactivity toward a broad spectrum of nucleophilic species (N-, P-, S-, and O-nucleophiles) to yield the corresponding difluoromethylated products with high efficacy under mild conditions. Additional studies have been performed to elucidate the mechanistic fundamentals of the reactions.
- Prakash, G.K. Surya,Zhang, Zhe,Wang, Fang,Ni, Chuanfa,Olah, George A.
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experimental part
p. 792 - 798
(2011/10/09)
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- A flash photolysis and theoretical study of the reaction of arylnitroso oxides with phosphorus(III) compounds
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The kinetic features of the reaction of aromatic nitroso oxides (ArNOO) with tri-n-butyl phosphite and substituted phosphines were studied by flash photolysis. It was shown that the trans-isomers of nitroso oxides enter into the reaction. The mechanism of the reaction was studied by theoretical methods, and the inertness of the cis-form of ArNOO was explained.
- Khursan,Kovaleva,Chainikova,Talipov,Safiullin
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experimental part
p. 284 - 289
(2011/11/12)
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- Synthesis, derivatisation and structural characterisation of a new macrobicyclic phosphane oxide cryptand
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Following a tripod-coupling strategy a new phosphane oxide cage compound was synthesised in comparatively high yield. The X-ray crystal structure obtained shows a large cavity and an out-positioned P=O moiety in the solid state. A stable in-isomer was not
- Daebritz, Frank,Jaeger, Anne,Bauer, Ingmar
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experimental part
p. 5571 - 5576
(2009/05/11)
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- Efficient aerobic oxidation of phosphines, phosphites, and sulfides by using trialkylborane
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Treatment of phosphines, phosphites, or sulfides with trialkylborane under air afforded the corresponding oxides in good yields.
- Motoshima, Kosuke,Sato, Akinori,Yorimitsu, Hideki,Oshima, Koichiro
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experimental part
p. 2229 - 2231
(2009/08/08)
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- Effects of substituents on aryl groups during the reaction of triarylphosphine radical cation and oxygen
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In a previous report (S. Yasui, S. Tojo and T. Majima, J. Org. Chem., 2005, 70, 1276), we presented the results from the laser flash photolysis (LFP) and product analysis of the 9,10-dicyanoanthracene (DCA)-photosensitized oxidation of triarylphosphine (Ar3P) in acetonitrile under air, which showed that the photoreaction results in the oxidation of Ar3P to give the corresponding phosphine oxide (Ar3PO) in a nearly quantitative yield, and that the reaction is initiated by the electron transfer (ET) from Ar 3P to DCA in the singlet excited state (1DCA*), producing the triarylphosphine radical cation Ar3P+. This radical cation decays through radical coupling with O2 to afford the peroxy radical cation Ar3P+-O-O, which we proposed to be the intermediate leading to the product Ar3PO. We now examined this photoreaction in more detail using ten kinds of Ar3P with various electronic and steric characteristics. The decay rate of Ar3P + measured by the LFP was only slightly affected by the substituents on the aryl groups of Ar3P. During the photolysis of trimesitylphosphine (Mes3P), the peroxy radical cation intermediate (Mes3P+-O-O) had a lifetime long enough to be spectrophotometrically detected. The quantum yields of Ar3PO increased with either electron-withdrawing or -releasing substituents on the aryl groups, suggesting that a radical center is developed on the phosphorus atom during the step when the quantum yield is determined. In addition, the o-methyl substituents in Ar3P decreased the quantum yield. These results clearly indicated that Ar3P+-O-O undergoes radical attack upon the parent phosphine Ar3P that eventually produces the final product, Ar3PO. The Royal Society of Chemistry 2006.
- Yasui, Shinro,Tojo, Sachiko,Majima, Tetsuro
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p. 2969 - 2973
(2008/02/11)
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- Reaction of triarylphosphine radical cations generated from photoinduced electron transfer in the presence of oxygen
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(Chemical Equation Presented) The 9,10-dicyanoanthracene (DCA)-sensitized photoreaction of triarylphosphines (1) was carried out in acetonitrile under aerobic conditions. Phosphine 1 was oxidized to the corresponding phosphine oxide with no appreciable side reactions. Product analysis and laser flash photolysis experiments suggest that the radical cation of 1 formed by the electron transfer from 1 to DCA in the singlet excited state ( 1DCA*) reacts with O2 to eventually afford the phosphine oxide.
- Yasui, Shinro,Tojo, Sachiko,Majima, Tetsuro
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p. 1276 - 1280
(2007/10/03)
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- Catalytic asymmetric cyano-ethoxycarbonylation reaction of aldehydes using a YLi3tris(binaphthoxide) (YLB) complex: Mechanism and roles of achiral additives
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Full details of a catalytic asymmetric cyano-ethoxycarbonylation reaction promoted by a heterobimetallic YLi3tris(binaphthoxide) complex (YLB 1), especially mechanistic studies, are described. In the cyanation reaction of aldehydes with ethyl c
- Yamagiwa, Noriyuki,Tian, Jun,Matsunaga, Shigeki,Shibasaki, Masakatsu
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p. 3413 - 3422
(2007/10/03)
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- Mechanisms of hydrogen-, oxygen-, and electron-transfer reactions of cumylperoxyl radical
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Rates of hydrogen-transfer reactions from a series of para-substituted N,N-dimethylanilines to cumylperoxyl radical and oxygen-transfer reactions from cumylperoxyl radical to a series of sulfides and phosphines have been determined in propionitrile (EtCN) and pentane at low temperatures by use of ESR. The observed rate constants exhibit first-order and second-order dependence with respect to concentrations of N,N-dimethylanilines. This indicates that the hydrogen- and oxygen-transfer reactions proceed via 1:1 charge-transfer (CT) complexes formed between the substrates and cumylperoxyl radical. The primary kinetic isotope effects are determined by comparing the rates of N,N-dimethylanilines and the corresponding N,N-bis(trideuteriomethyl)anilines. The isotope effect profiles are quite different from those reported for the P-450 model oxidation of the same series of substrates. Rates of electron-transfer reactions from ferrocene derivatives to cumylperoxyl radical have also been determined by use of ESR. The catalytic effects of Sc(OTf)3 (OTf = triflate) on the electron-transfer reactions are compared with those of Sc(OTf)3 on the hydrogen- and oxygen-transfer reactions. Such comparison provides strong evidence that the hydrogen- and oxygen- transfer reactions of cumylperoxyl radical proceed via a one-step hydrogen atom and oxygen atom transfer rather than via an electron transfer from substrates to cumylperoxyl radical.
- Fukuzumi, Shunichi,Shimoosako, Kanji,Suenobu, Tomoyoshi,Watanabe, Yoshihito
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p. 9074 - 9082
(2007/10/03)
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- Stoichiometric and catalytic oxygen activation by trimesityliridium(III)
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Trimesityliridium(III) (mesityl = 2,4,6-trimethylphenyl) reacts with O2 to form oxotrimesityliridium(V), (mes)3Ir=O, in a reaction that is cleanly second order in iridium. In contrast to initial reports by Wilkinson, there is no evidence for substantial accumulation of an intermediate in this reaction. The oxo complex (mes)3Ir=O oxidizes triphenylphosphine to triphenylphosphine oxide in a second-order reaction with ΔH? = 10.04 ± 0.16 kcal/mol and ΔS? = -21.6 ± 0.5 cal/(mol·K) in 1,2-dichloroethane. Triphenylarsine is also oxidized, though over an order of magnitude more slowly. Ir(mes)3 binds PPh3 reversibly (Kassoc = 84 ± 3 M-1 in toluene at 20°C) to form an unsymmetrical, sawhorse-shaped four-coordinate complex, whose temperature-dependent NMR spectra reveal a variety of dynamic processes. Oxygen atom transfer from (mes)3Ir=O and dioxygen activation by (mes)3Ir can be combined to allow catalytic aerobic oxidations of triphenylphosphine at room temperature and atmospheric pressure with overall activity (~60 turnovers/h) comparable to the fastest reported catalysts. A kinetic model that uses the rates measured for dioxygen activation, atom transfer, and phosphine binding describes the observed catalytic behavior well. Oxotrimesityliridium does not react with sulfides, sulfoxides, alcohols, or alkenes, apparently for kinetic reasons.
- Jacobi, Bridey Grant,Laitar, David S.,Pu, Lihung,Wargocki, Michael F.,DiPasquale, Antonio G.,Fortner, Kevin C.,Schuck, Stephany M.,Brown, Seth N.
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p. 4815 - 4823
(2008/10/08)
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- Kinetic study on denomination of vic-dibromides with trivalent phosphorus compounds
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Various types of trivalent phosphorus compounds (I) brought about reductive debromination of vic-dibromides (2) to afford olefins. The reaction was accelerated by either electron-releasing substituents on the phosphorus of 1 or electron-with-drawing substituants on the α-carbon of 2. The substituent effects, along with the stereochemistry of the reaction, are consistent with an E1CB-like mechanism for the elimination of the two bromine atoms. That is, 1 initially undergoes nucleophilic attack upon a bromine of 2. At the transition state, a fractional positive charge is developed on the phosphorus of 1 and a fractional negative charge on the carbon of 2. This mechanism suggests the importance of an electronic character of the vic-dibromide in determining the relative ease of bromophilicity, carbophilicity, and basicity of the phosphorus of a trivalent phosphorus compound in a reaction with the dibromide. α 2001 John Wiley & Sons, Inc.
- Yasui, Shinro
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p. 217 - 222
(2007/10/03)
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- A new palladium-catalyzed P-C coupling reaction: Synthesis of triarylphosphine oxides and diarylmethylphosphine oxides
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The first palladium-catalyzed P-C coupling reaction of aryl halides with (hydroxymethyl)phosphines is described. Hydroxymethylphosphines act as cheap and easy to use H3PO and CH3P(O)H2 equivalents. Tertiary diarylmethylphosphine oxides 5 and triarylphosphine oxides 6 are accessible in a one pot reaction in overall yields between 45-60%.
- Stark, Gene A.,Riermeier, Thomas H.,Beller, Matthias
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p. 1703 - 1711
(2007/10/03)
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- Quenching of a photosensitized dye through single-electron transfer from trivalent phosphorus compounds
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Various types of trivalent phosphorus compounds 1 undergo single-electron transfer (SET) to the photoexcited state of rhodamine 6G (Rho+(*)) in aqueous acetonitrile to quench the fluorescence from Rho+(*). The rate constants k(p) for the overall SET process were determined by the Stern-Volmer method. The rate is nearly constant at a diffusion-controlled limit in the region of E( 1/2 )(1) +), whereas log k(p) depends linearly on E( 1/2 )(1) in the region of E( 1/2 )(1) > 1.3 V, the slope of the correlation line being -αF/RT with α = 0.2. The potential at which the change in dependence of log k(p) on E( 1/2 )(1) occurs (1.3 V) is in accordance with the value of E( 1/2 )(Rho+(*)) (1.22 V) that has been obtained experimentally. Thus, the SET step is exothermic when E( 1/2 )(1) 1.3 V. The α-value (0.2) obtained in the endothermic region shows that the SET step from 1 to Rho+(*)is irreversible in this region. Trivalent phosphorus radical cation 1(·+) generated in the SET step undergoes an ionic reaction with water in the solvent rapidly enough to make the SET step irreversible. In contrast, the SET from amines 2 and alkoxybenzenes 3 to Rho+(*) is reversible when the SET step is endothermic, meaning that the radical cations 2(·+) and 3(·+) generated in the SET step undergo rapid 'back SET' in the ground state to regenerate 2 and 3.
- Yasui, Shinro,Tsujimoto, Munekazu,Itoh, Kenji,Ohno, Atsuyoshi
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p. 4715 - 4720
(2007/10/03)
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- N2O oxidation of phosphines catalyzed by low-valent nickel complexes
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In the presence of a catalytic amount of the nickel(0) complex derived from Ni(acac)2 or NiCl2 with DIBAL or BuLi, nitrous oxide (N2O) was captured and activated to oxidize phosphine(III) into the corresponding phosphine oxide. Bidentate phosphines, for example, 1,3-bis(diphenyl-phosphino)propane (dppp), were employed as effective ligands for N2O; oxidation and were recovered after the reaction.
- Yamada, Tohru,Suzuki, Kyosuke,Hashimoto, Kentaro,Ikeno, Taketo
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p. 1043 - 1044
(2007/10/03)
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- Oxidations of ER3 (E = P, As, or Sb) by hydrogen peroxide. Methylrhenium trioxide as catalyst
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Catalytic and noncatalytic conversions of tertiary phosphines to their oxides by hydrogen peroxide have been investigated. The catalyst is methylrhenium trioxide, CH3ReO3. The kinetics were investigated in acetonitrile-water (1:1 by volume) at 25°C. Stepwise interactions between CH3ReO3 and H2O2 form CH3Re(η2-O2)(O)2(OI2). A, and CH3Re(η2-O2)2(O)(OH2), B. In CH3CN-H2O (1:1 v/v) the equilibrium constants are K1 = 13 ± 2 L mol-1 and K2 = 136 ± 28 L mol-1 at pH 1.0 and 25°C. The forward and reverse rate constants for the formation of A in this medium are k1 = 32.5 ± 0.3 L mol-1 s-1 and k-1 - 3.0 ± 0.2 s-1. Systematic changes in the substituents on phosphorus were made to vary the nucleophilicity of the phosphine and its cone angles; the kinetic effects are discernible, although they lie in a narrow range. Triphenylarsine and triphenylstibine were also studied, and their rates are within a factor of 2 of that for PPh3. The rhenium peroxides A and B show a small difference in reactivity. The bimolecular reactions between A and most of the phosphines have rate constants of the order 105 L mol-1 s-1. The kinetic data support a mechanism that allows nucleophilic attack of the substrate at the rhenium peroxides.
- Abu-Omar,Espenson
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p. 272 - 280
(2007/10/02)
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- N-Phenyl-P,P,P-triarylphospha-λ5-azenes, Triarylphosphines, and Triarylphosphine Oxides. Substituent Effects on 15N, 31P, and 13C NMR Spectra
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The syntheses and 15N, 31P, and 13C NMR spectra of a series of N-phenyl-P,P,P-triarylphospha-λ5-azenes 4 and the 31P and 13C NMR spectra of the corresponding series of triarylphosphines 5 and triarylphosphine oxides 6 are reported.The substituent effects on the chemical shifts can be best accommodated and rationalized by use of a model for system 4 whereby the dipole of the aryl group and its pendant R group polarizes the rest of the molecule.This includes the P and N atoms and phenyl ring, where an electron-withdrawing R group increases the electron density of the P, N, and ipso C-1 while decreasing the electron density on C-3 and C-4 of the N-phenyl ring (Figure 3).A similar polarization pattern for the phosphine oxide series 6 is suggested.In the phosphine series 5, the chemical shift data is consistent with the lone electron pair on the phosphorus atom delocalizing into the aryl rings.The coupling constant data, in particular 1JPN for series 4 and 1JPC for series 4-6, were examined with use of the Hammett monosubstituent parameter (MSP) and the Taft dual-substituent parameter (DSP) approaches.For systems 4 and 6, without a lone electron pair on the phosphorus atom, a better electron-donating substituent increases the one-bond P-C(Ar) coupling constant.On the contrary, in the phosphine series 5, where there is a lone electron pair on the phosphorus, a better electron-withdrawing substituent increases the one-bond P-C(Ar) coupling constant.DSP treatment of 1JPC, and comparing to the few related systems in the literature,shows three types of systems.One, which includes 4 and 6, has an atom, phosphorus in these cases, that does not have a lone pair of electrons attached to the ring to which is attached an atom with a lone pair of electrons.Here, the resonance effect on 1JPC predominates.A second series, which includes phosphines 5, has a lone pair on the atom attached to the aryl ring.In these cases, the resonance effect is ca. 50percent greater than the inductive effect.Finally, the third series, exemplified by two examples from the literature, has a tetrahedral atom (without a lone pair) attached to the aryl ring and this in turn is attached to tetrahedral atoms without lone electron pairs.In these case, the resonance and inductive effects are fairly comparable.
- Chou, Whe-Narn,Pomerantz, Martin
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p. 2762 - 2769
(2007/10/02)
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- The Mechanisms of the Conversion of Thiophosphoryl Compounds into their Phosphoryl Analogues by Photochemically Excited 3-Methylpyridazine 2-Oxide and by 2-Methyl-3-p-nitrophenyloxaziridine; a Comparison
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Reactions of tri-p-substituted triarylphosphine sulphides with 3-methylpyridazine 2-oxide, under photolysis, and with 2-methyl-3-p-nitrophenyloxaziridine both give the corresponding phosphine oxides.A detailed study and comparison of the two reactions shows that they are mechanistically quite distinct and that it is unlikely that the active oxygenating species generated by photolysis of the N-oxide, which attacks the phosphine sulphides, is an oxaziridine.The evidence presented suggests that this species may in fact be 'oxene'.
- Rowley, Alan G.,Steedman, John R. F.
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p. 1113 - 1120
(2007/10/02)
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- Reaction of Triarylphosphines with Tetramethyl-1,2-dioxetane: Kinetics of Formation and Decomposition of 2,2-Dihydro-4,4,5,5-tetramethyl-2,2,2-triaryl-1,3,2-dioxaphospholanes
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The reaction of a series of triarylphosphines with tetramethyl-1,2-dioxetane (1) in C6D6 produced a series of 2,2-dihydro-4,4,5,5-tetramethyl-2,2,2-triaryl-1,3,2-dioxaphospholanes in high yield.Thermal decomposition of the phosphoranes produced tetramethylethylene oxide and the corresponding triarylphosphine oxides in all cases.The kinetics of phosphorane formation and decomposition in benzene was investigated.The rate data for phosphorane formation showed a reasonable correlation with ?+ constants (correlation coefficient ca 0.98: ρ = -0.82).Theresults are not consistent with nucleophilic attack on oxygen by phosphorus but rather with a concerted (biphilic) insertion into the peroxy bond of the dioxetane.Phosphorane decomposition (at 38 deg C) was found to be substantially more sensitive to substituent effects than phosphorane formation.A good correlation of phosphorane decomposition with Hammett ? constants was obtained (correlation coefficient = 0.997, ρ = -3.51 +/- 0.24).This result is consistent with a mechanism that involves heterolytic cleavage of a phosphorus-oxygen bond followed by the irreversible internal displacement of triarylphosphine oxide.
- Baumstark, Alfons L.,McCloskey, Candice J.,Williams, Timothy E.,Chrisope, Douglas R.
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p. 3593 - 3597
(2007/10/02)
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