- Addition reactions of a phosphorus triamide to nitrosoarenes and acylpyridines
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Tricoordinate phosphorus compounds react with a wide variety of double bonds through addition reactions. The dipolar and cyclic products formed are important intermediates in organophosphorus chemistry. We investigated the reactivity between phosphorus triamide 1 and nitrosoarenes and 2-acylpyridines. For sterically congested substrates, the formation of σ5,λ5-phosphorus products is observed. DFT calculations indicate this product is formed through a concerted [4 + 1] mechanism. For less sterically congested substrates, products are observed arising from cleavage of the N = O or C = O bond with formation of a terminal P = O bond and aryl nitrene or carbene migration into a P–N bond of the phosphorus triamide core. DFT calculations are consistent with an initial [2 + 1] addition to phosphorus followed by formal carbene/nitrene migration in these cases.
- Mattos, Jared T.,Radosevich, Alexander T.,te Grotenhuis, Colet
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p. 940 - 946
(2020/10/02)
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- Organo-peroxyl compounds via catalytic oxidation of a hindered phenol and aniline utilizing new manganese(II) bis benzimidazole diamide based complexes
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Bis benzimidazole diamide ligand-N,N′-bis(2-methylbenzimidazolyl) propanediamide [GBMA = L] has been synthesized and utilized to prepare new Mn(II) complexes of general composition [Mn(L)X2]·nH 2O where X is an exogenous anionic ligand(X = Cl-, CH 3COO-, SCN-). The geometry of the ligand and its Mn(II) complex have been optimized at the level of UHF, by using ZINDO/1 method. Binding energies, heat of formation and bond lengths of geometry optimized structures for the ligand and complex have been obtained. The oxidation of 2,4,6-tri-tert.-butylphenol (TTBP) and 2,4,6-tri-tert.-butylaniline (TTBA) has been investigated using these Mn(II) complexes as catalyst and TBHP as an alternate source of oxygen. The organo-peroxyl compounds have been isolated and characterized by 1H NMR, 13C NMR, IR and mass data. A different product profile was obtained when H2O2 is used as an oxidant.
- Bakshi, Ruchi,Mathur, Pavan
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experimental part
p. 3477 - 3488
(2011/02/15)
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- Catalytic oxidation of a trialkyl-substituted phenol and aniline with biomimetic schiff base complexes
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The catalytic oxidation of 2,4,6-tri-tert-butylphenol and 2,4,6-tri-tert-butylaniline with molecular oxygen and tert-butylhydroperoxide was investigated using biomimetic Mn-, Fe- and Co-complexes as catalysts. The catalytic activity and product distribution were determined and compared with those observed in the reactions of the well-known Co(salen) complex.
- Knaudt, Jutta,Foerster, Stefan,Bartsch, Ulrich,Rieker, Anton,Jaeger, Ernst-G.
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- Cobalt schiff base complex-catalyzed oxidation of anilines with tert-butyl hydroperoxide
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Cobalt Schiff base complexes [Co(SB)] catalyze the oxidation of anilines (1) with tert-butyl hydroperoxide to give nitrobenzenes 2 and 4-(tert-butylperoxy)-2,5-cyclohexadien-1-imine derivatives 3 in yield distributions depending on the substitution mode of the substrate. 4-Alkyl- and 4-aryl-2,6-di-tert-butylanilines gave mixtures of 2 and 3, where the higher the bulkiness of the 4-substituent, the higher the yield of 2. With 2,4,6-trimethylaniline, the ratio of oxidations of the nitrogen and C-4 atoms was almost the same; but a hydrolyzed product 5 of the imine was obtained. 2,4,6-Triphenylaniline gave only 2. Nitrobenzene derivatives were also obtained from 2,6-dialkylanilines and 4-substituted anilines. The catalytic activity of Co(SB) depended on the nature of the SB ligand: the formal potential E° and steric factors seem to affect the reaction rate. Kinetic studies showed that the key step may involve hydrogen abstraction from the aniline, presumably by t-BuO? generated from homolytic decomposition of initially formed CoIII(SB)(OO-t-Bu). A precursor of 2 was found to be the nitrosobenzene derivative.
- Foerster, Stefan,Rieker, Anton,Maruyama, Kazushige,Murata, Kunihiko,Nishinaga, Akira
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p. 3320 - 3326
(2007/10/03)
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- Monomer-Dimer Solution Equilibria of 2,4,6-Trialkylnitrosobenzenes and 2,4,6-Trialkylnitrosobenzene/Nitrosobenzene Mixtures. A Study Using One- and Twodimensional NMR Techniques
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2,4,6-Trimethylnitrosobenzene in CDCl3 exists as a mixture of monomer and Z- and E-azodioxy dimers.The dissociation kinetics of both dimers were measured by one-dimensional time-dependent NMR spectroscopy on non-equilibrium solutions, and by two-dimensional exchange spectroscopy (2D-EXSY) on equilibrium solutions. 2,4,6-Tri-t-butylnitrosobenzene is entirely monomeric in CDCl3 but forms mixed azodioxy dimers in the presence of nitrosobenzene.The dissociation kinetics of the mixed E-dimer were followed by NMR techniques.The activation energy parameters for these dissociation equilibria were compared with previous data on related nitrosobenzene and dimethylnitrosobenzene systems.
- Orrell, Keith G.,Stephenson, David,Verlaque, James H.
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p. 1297 - 1303
(2007/10/02)
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