- 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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- A Synthetic Oxygen Atom Transfer Photocycle from a Diruthenium Oxyanion Complex
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Three new diruthenium oxyanion complexes have been prepared, crystallographically characterized, and screened for their potential to photochemically unmask a reactive Ru - Ru=O intermediate. The most promising candidate, Ru2(chp)4ONO
- Corcos, Amanda R.,Pap, József S.,Yang, Tzuhsiung,Berry, John F.
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- Kinetics and mechanism of PPh3 oxygenation with 3O2 catalyzed by a 1,3,2-oxazaphosphole as flavin mimic
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A 1,3,2-oxazaphosphole picks up triplet dioxygen in 1:1 stoichiometry similar to flavin organic co-factors. 1,3,2-Oxazaphosphole catalyzes the oxygenation of triphenylphosphine to triphenylphosphine oxide. The reaction obeys an overall third order rate eq
- Bors,Kaizer,Speier
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- Ligand-Constraint-Induced Peroxide Activation for Electrophilic Reactivity
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μ-1,2-peroxo-bridged diiron(III) intermediates P are proposed as reactive intermediates in various biological oxidation reactions. In sMMO, P acts as an electrophile, and performs hydrogen atom and oxygen atom transfers to electron-rich substrates. In cyanobacterial ADO, however, P is postulated to react by nucleophilic attack on electrophilic carbon atoms. In biomimetic studies, the ability of μ-1,2-peroxo-bridged dimetal complexes of Fe, Co, Ni and Cu to act as nucleophiles that effect deformylation of aldehydes is documented. By performing reactivity and theoretical studies on an end-on μ-1,2-peroxodicobalt(III) complex 1 involving a non-heme ligand system, L1, supported on a Sn6O6 stannoxane core, we now show that a peroxo-bridged dimetal complex can also be a reactive electrophile. The observed electrophilic chemistry, which is induced by the constraints provided by the Sn6O6 core, represents a new domain for metal?peroxide reactivity.
- Ansari, Mursaleem,Chandra, Anirban,Kundu, Subrata,Monte-Pérez, Inés,Rajaraman, Gopalan,Ray, Kallol
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supporting information
p. 14954 - 14959
(2021/06/01)
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- Deuteriodifluoromethylation and gem-Difluoroalkenylation of Aldehydes Using ClCF2H in Continuous Flow
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The deuteriodifluoromethyl group (CF2D) represents a challenging functional group due to difficult deuterium incorporation and unavailability of precursor reagents. Herein, we report the use of chlorodifluoromethane (ClCF2H) gas in t
- Fu, Wai Chung,Jamison, Timothy F.
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p. 13885 - 13890
(2020/06/10)
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- A Mn(iv)-peroxo complex in the reactions with proton donors
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Protons play an important role in promoting O-O or M-O bond cleavage of metal-peroxo complexes. Treatment of side-on O2-bound [PPN][MnIV(TMSPS3)(O2)] (1, PPN = bis(triphenylphosphine)iminium and TMSPS
- Lee, Chien-Ming,Sankaralingam, Muniyandi,Chuo, Chi-He,Tseng, Tzu-Hsien,Chen, Peter P.-Y.,Chiang, Ming-Hsi,Li, Xiao-Xi,Lee, Yong-Min,Nam, Wonwoo
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p. 5203 - 5213
(2019/04/27)
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- On the incompatibility of lithium-O2 battery technology with CO2
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When solubilized in a hexacarboxamide cryptand anion receptor, the peroxide dianion reacts rapidly with CO2 in polar aprotic organic media to produce hydroperoxycarbonate (HOOCO2-) and peroxydicarbonate (-O2COOCO2-). Peroxydicarbonate is subject to thermal fragmentation into two equivalents of the highly reactive carbonate radical anion, which promotes hydrogen atom abstraction reactions responsible for the oxidative degradation of organic solvents. The activation and conversion of the peroxide dianion by CO2 is general. Exposure of solid lithium peroxide (Li2O2) to CO2 in polar aprotic organic media results in aggressive oxidation. These findings indicate that CO2 must not be introduced in conditions relevant to typical lithium-O2 cell configurations, as production of HOOCO2- and -O2COOCO2- during lithium-O2 cell cycling will lead to cell degradation via oxidation of organic electrolytes and other vulnerable cell components.
- Zhang, Shiyu,Nava, Matthew J.,Chow, Gary K.,Lopez, Nazario,Wu, Gang,Britt, David R.,Nocera, Daniel G.,Cummins, Christopher C.
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p. 6117 - 6122
(2017/08/29)
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- Phosphine-promoted cyclization of dicyclopropenones
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A novel phosphine-promoted intramolecular cyclization of dicyclopropenones 1 has been described in this contribution. A variety of 2,3-dihydro-1H-indene-4, 6-diol derivatives 2 and hexahydropentalen-2-one derivatives 3 were obtained selectively in moderat
- Yang, Jin-Ming,Tang, Xiang-Ying,Wei, Yin,Shi, Min
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supporting information
p. 3545 - 3552
(2014/01/06)
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- Recyclable hypervalent iodine(III) reagent iodosodilactone as an efficient coupling reagent for direct esterification, amidation, and peptide coupling
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A hypervalent iodine(III) reagent plays a novel role as an efficient coupling reagent to promote the direct condensation between carboxylic acids and alcohols or amines to provide esters, macrocyclic lactones, amides, as well as peptides without racemization. The regeneration of iodosodilactone (1) can also be readily achieved. The intermediate acyloxyphosphonium ion C from the activation of a carboxylic acid is thought to be involved in the present esterification reaction.
- Tian, Jun,Gao, Wen-Chao,Zhou, Dong-Mei,Zhang, Chi
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supporting information; experimental part
p. 3020 - 3023
(2012/08/07)
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- Effects of phosphorus substituents on reactions of α- alkoxyphosphonium salts with nucleophiles
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The effects of phosphorus substituents on the reactivity of α-alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α-alkoxyphosphonium salts, prepared from various acetals and tris(o-tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high-yielding nucleophilic substitution reactions of α-alkoxyphosphonium salts. The reactivity of these salts was determined by a balance between steric and electronic factors, respectively, represented by cone angles θ and CO stretching frequencies ν (steric and electronic parameters, respectively). In addition, a novel reaction of α-alkoxyphosphonium salts derived from Ph3P with Grignard reagents was observed to take place in the presence of O2 to afford alcohols in good yields. A radical mechanism is proposed for this process that has gained support from isotope-labeling and radical-inhibition experiments. A dramatic change in the reactivity of an α-alkoxyphosphonium salt toward nucleophiles is observed due to the steric and electronic nature of the phosphine substituents. By changing the type of phosphorus substituents, the reaction pathway can be controlled to proceed selectively by substitution or a new radical reaction (see scheme; OTf=trifluoromethansulfonate, TMS=trimethylsilyl, o-tol=tolyl). Copyright
- Goto, Akihiro,Otake, Kazuki,Kubo, Ozora,Sawama, Yoshinari,Maegawa, Tomohiro,Fujioka, Hiromichi
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p. 11423 - 11432
(2012/11/07)
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- Dehydrative glycosylation with the Hendrickson reagent
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The Hendrickson reagent is able to perform efficiently dehydrative glycosylation of 1-hydroxyglycosyl donors. The reaction occurs under mild conditions through an anomeric oxophosphonium intermediate detected by nuclear magnetic resonance. Further insight into the mechanism was gained by 18O labeling of anomeric OH.
- Mossotti, Matteo,Panza, Luigi
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body text
p. 9122 - 9126
(2011/12/16)
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- A manganese(V)-oxo π-cation radical complex: Influence of one-electron oxidation on oxygen-atom transfer
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One-electron oxidation of MnV-oxo corrolazine 2 affords 2 +, the first example of a MnV(O) π-cation radical porphyrinoid complex, which was characterized by UV-vis, EPR, LDI-MS, and DFT methods. Access to 2 and 2+ allowed for a direct comparison of their reactivities in oxygen-atom transfer (OAT) reactions. Both complexes are capable of OAT to PPh3 and RSR substrates, and 2+ was found to be a more potent oxidant than 2. Analysis of rate constants and activation parameters, together with DFT calculations, points to a concerted OAT mechanism for 2+ and 2 and indicates that the greater electrophilicity of 2+ likely plays a dominant role in enhancing its reactivity. These results are relevant to comparisons between Compound I and Compound II in heme enzymes.
- Prokop, Katharine A.,Neu, Heather M.,De Visser, Sam P.,Goldberg, David P.
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body text
p. 15874 - 15877
(2011/11/13)
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- Stereoselective olefination of N-sulfonyl imines with stabilized phosphonium ylides for the synthesis of electron-deficient alkenes
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An unprecedented protocol has been developed for thestereoselective synthesis of structurally diverse electron-deficient alkenes in moderate to excellent yields from readily accessible N-sulfonyl imines and stabilized phosphonium ylides. Significantly, the olefination reaction of N-sulfonylimines with nitrile-stabilized phosphonium ylides affords an array of α,β-unsaturated nitriles with high Z selectivity, and the reactions with ester-, amide-, and ketone-stabilized phosphonium ylides afford α,β-unsaturated esters, amides, and ketones with high E selectivity, respectively. Spectroscopic analysis of the reaction mixtures and trapping of the intermediates allow plausible mechanisms to be proposed. Initialimine/ylide addition leads to the formation of betaines that cyclize to form 1,2-azaphosphetanes that subsequently eliminate iminophosphoranes to yield alkenes. For the synthesis of electron-deficient 1,2-disubstituted alkenes, the presence of an electron-withdrawing group in the betaine allows rapid interconversion between its two diastereomers through proton transfer. The Z/E selectivity for alkene synthesis is determined by the different rates at which the two betaine diastereomers form the corresponding 1,2-azaphosphetane diastereomers. In contrast, the Z/E selectivity for the synthesis of electron-deficient trisubstituted alkenes originates from the diastereoselective addition of stabilized phosphonium ylides to N-sulfonyl imines.
- Fang, Fan,Li, Yuan,Tian, Shi-Kai
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supporting information; experimental part
p. 1084 - 1091
(2011/04/15)
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- Tunable stereoselective alkene synthesis by treatment of activated imines with nonstabilized phosphonium ylides
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A broad range of readily accessible N-sulfonyl imines undergo olefination reaction with nonstabilized phosphonium ylides under mild conditions to afford an array of both Z- and E-isomers of 1,2-disubstituted alkenes, allylic alcohols, and allylic amines in good yields and with greater than 991 stereoselectivity.
- Dong, De-Jun,Li, Yuan,Wang, Jie-Qi,Tian, Shi-Kai
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supporting information; experimental part
p. 2158 - 2160
(2011/03/20)
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- An unusual reaction of α-alkoxyphosphonium salts with Grignard reagents under an O2 atmosphere
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An unusual and novel reaction of α-alkoxyphosphonium salts, generated from O,O-acetals and Ph3P, with Grignard reagents under an O 2 atmosphere afforded alcohols in moderate to high yields. It was clarified by isotopic labelling experiments that the reaction proceeded via a novel radical pathway.
- Fujioka, Hiromichi,Goto, Akihiro,Otake, Kazuki,Kubo, Ozora,Sawama, Yoshinari,Maegawa, Tomohiro
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p. 9894 - 9896
(2011/10/09)
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- Activation of molecular oxygen by a dioxygenase pathway by a ruthenium bis-bipyridine compound with a proximal selenium site
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A ruthenium(II) bipyridine complex with proximal phenylselenium tethers, [Ru](H2O)2, reacted intramolecularly with O2 in a protic slightly acidic solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), to yield an O-O bond cleaved product, [Ru](O)2, with formation of two Ru-O-Se moieties. This stable compound was isolated, and its structure was determined by X-ray diffraction. The identification of the compound in solution was confirmed by ESI-MS and the 1H NMR with the associated Curie plot that showed that [Ru](O)2 was paramagnetic. The magnetic susceptibility was 2.8 μB by Evan's method suggesting a ground state triplet or biradical. DFT calculations, however, predicted a ground state singlet and an oxidized Se atom. Further it was shown that [Ru](O)2 is a potent oxygen transfer species of both O2-derived atoms to triphenylphosphine and a nucleophilic alkene such as 2,3-dimethyl-2-butene in both HFIP and acetonitrile. UV-vis spectroscopy combined with the measured stoichiometry of PPh3:O2 = 2 in a catalytic oxidation of PPh3 suggests a dioxygenase type activation of O 2 with structural identification of the O-O bond cleavage reaction step, formation of [Ru](O)2 as an intermediate, and the proof that [Ru](O)2 is a donor of both oxygen atoms.
- Laskavy, Alexander,Shimon, Linda J. W.,Konstantinovski, Leonid,Iron, Mark A.,Neumann, Ronny
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body text
p. 517 - 523
(2010/03/25)
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- Stereospecific deoxygenation of phosphine oxides with retention of configuration using triphenylphosphine or triethyl phosphite as an oxygen acceptor
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(Chemical Equation Presented) A new protocol for deoxygenation of various phosphine oxides with retention of configuration is described. The advantage of the new method includes milder conditions and considerably shortened reaction times. Mechanistic studies about the oxygen transfer between the starting phosphine oxide and the sacrificial triphenylphosphine are also presented.
- Wu, Hai-Chen,Yu, Jin-Quan,Spencer, Jonathan B.
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p. 4675 - 4678
(2007/10/03)
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- A stable manganese(V)-oxo corrolazine complex
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The synthesis and characterization of an oxomanganese(V) corrolazine, (TBP) 8(Cz)Mn(V)O≡ (2), are reported. This remarkably stable high-valent complex is obtained from the stoichiometric reaction of (TBP) 8(Cz)Mn(III) (1) with m-CPBA and is easily purified by standard chromatographic methods on silica gel at room temperature. Complex 2 exhibits a diamagnetic 1H NMR spectrum indicative of a low-spin d 2 Mn(V)O≡ species. LDI-TOFMS of 2 shows the predicted isotopic envelope at m/z 1426.8. This envelope shifts to higher mass as expected after the facile exchange of the terminal oxo group with H218O. The resonance Raman spectrum of 2 either in solution or in the solid state shows a strongly enhanced Raman band for the stretching mode of the Mn-oxo bond, which also shifts as expected upon 18O substitution: 2(16O), 979 cm-1; 2(18O), 938 cm-1 (in CH2Cl2). Initial reactivity studies show that 2 rapidly transfers the terminal oxo ligand to PPh3, resulting in the quantitative formation of OPPh3 and concomitant reduction of 2 back to 1. Complex 2 is the first example of an oxomanganese(V)-porphyrinoid complex that can be isolated at room temperature. Copyright
- Mandimutsira, Beaven S.,Ramdhanie, Bobby,Todd, Ryan C.,Wang, Hailin,Zareba, Adelajda A.,Czernuszewicz, Roman S.,Goldberg, David P.
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p. 15170 - 15171
(2007/10/03)
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- Oxygen Atom Transfer in the Oxidation of Triphenylphosphine by μ-Oxo-bis
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It has been shown that μ-oxo-bis can oxidize triphenylphosphine to triphenylphosphine oxide in the presence of pyridine under mild conditions, resulting in the formation of the corresponding FeII-bis adduct; this reaction is a rare example of O atom transfer by a μ-oxo FeIII oligomer.
- Ercolani, Claudio,Gardini, Marcello,Pennesi, Giovanna,Rossi, Gentilina
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p. 549 - 550
(2007/10/02)
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