1191-95-3Relevant articles and documents
Formation of a Ruthenium(V) - Imido complex and the reactivity in substrate oxidation in water through the nitrogen non-rebound mechanism
Ishizuka, Tomoya,Kogawa, Taichi,Makino, Misaki,Shiota, Yoshihito,Ohara, Kazuaki,Kotani, Hiroaki,Nozawa, Shunsuke,Adachi, Shin-Ichi,Yamaguchi, Kentaro,Yoshizawa, Kazunari,Kojima, Takahiko
, p. 12815 - 12824 (2019)
A RuII - NH3 complex, 2, was oxidized through a proton-coupled electron transfer (PCET) mechanism with a CeIV complex in water at pH 2.5 to generate a RuV═NH complex, 5. Complex 5 was characterized with various spectroscopies, and the spin state was determined by the Evans method to be S = 1/2. The reactivity of 5 in substrate C-H oxidation was scrutinized in acidic water, using water-soluble organic substrates such as sodium ethylbenzene-sulfonate (EBS), which gave the corresponding 1-phenylethanol derivative as the product. In the substrate oxidation, complex 5 was converted to the corresponding RuIII - NH3 complex, 3. The formation of 1-phenylethanol derivative from EBS and that of 3 indicate that complex 5 as the oxidant does not perform nitrogen-atom transfer, in sharp contrast to other high-valent metal-imido complexes reported so far. Oxidation of cyclobutanol by 5 afforded only cyclobutanone as the product, indicating that the substrate oxidation by 5 proceeds through a hydride-transfer mechanism. In the kinetic analysis on the C-H oxidation, we observed kinetic isotope effects (KIEs) on the C-H oxidation with use of deuterated substrates and remarkably large solvent KIE (sKIE) in D2O. These positive KIEs indicate that the rate-determining step involves not only cleavage of the C-H bond of the substrate but also proton transfer from water molecules to 5. The unique hydride-transfer mechanism in the substrate oxidation by 5 is probably derived from the fact that the RuIV - NH2 complex (4) formed from 5 by 1e-/1H+ reduction is unstable and quickly disproportionates into 3 and 5.
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Morton,D.R. et al.
, p. 4349 - 4357 (1970)
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Mechanism of alcohol oxidation mediated by copper(II) and nitroxyl radicals
Ryland, Bradford L.,McCann, Scott D.,Brunold, Thomas C.,Stahl, Shannon S.
, p. 12166 - 12173 (2014)
2,2′-Bipyridine-ligated copper complexes, in combination with TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), are highly effective catalysts for aerobic alcohol oxidation. Considerable uncertainty and debate exist over the mechanism of alcohol oxidation mediated by CuII and TEMPO. Here, we report experimental and density functional theory (DFT) computational studies that distinguish among numerous previously proposed mechanistic pathways. Oxidation of various classes of radical-probe substrates shows that long-lived radicals are not formed in the reaction. DFT computational studies support this conclusion. A bimolecular pathway involving hydrogen-atom-transfer from a CuII-alkoxide to a nitroxyl radical is higher in energy than hydrogen transfer from a CuII-alkoxide to a coordinated nitroxyl species. The data presented here reconcile a collection of diverse and seemingly contradictory experimental and computational data reported previously in the literature. The resulting Oppenauer-like reaction pathway further explains experimental trends in the relative reactivity of different classes of alcohols (benzylic versus aliphatic and primary versus secondary), as well as the different reactivity observed between TEMPO and bicyclic nitroxyls, such as ABNO (ABNO = 9-azabicyclo[3.3.1]nonane N-oxyl).
Controlled synthesis of hydroxyapatite-supported palladium complexes as highly efficient heterogeneous catalysts
Mori, Kohsuke,Yamaguchi, Kazuya,Hara, Takayoshi,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 11572 - 11573 (2002)
Achieving precise control of active species on solid surfaces is one of the most important goals in the development of highly functionalized heterogeneous catalysts. The treatment of hydroxyapatites with PdCl2(PhCN)2 gives two new types of hydroxyapatite-bound Pd complexes. Using the stoichiometric hydroxyapatite, Ca10(PO4)6(OH)2, we found that monomeric PdCl2 species can be grafted on its surface, which are easily transformed into Pd0 particles with narrow size distribution in the presence of alcohols. Such metallic Pd species can effectively promote alcohol oxidation using molecular oxygen and are shown to give a remarkably high TON of up to 236000. Another monomeric PdII phosphate complex can be generated at a Ca-deficient site of the nonstoichiometric hydroxyapatite, Ca9(HPO4)(PO4)5(OH), affording a catalyst with PdII structure and high activity for the Heck and Suzuki reactions. To the best of our knowledge, the PdHAP are one of the most active heterogeneous catalysts for both alcohol oxidation under an atmospheric O2 pressure and the Heck reaction reported to date. These Pd catalysts are recyclable in the above organic reactions. Our approach to catalyst preparation based on the control of Ca/P ratios of hydroxyapatites represents a particularly attractive method for the nanoscale design of catalysts. Copyright
Seebach et al.
, p. 300,302 (1968)
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Semenow et al.
, p. 3221 (1956)
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Transition-Metal-Free Ring-Opening Reaction of 2-Halocyclobutanols through Ring Contraction
?ubiňák, Marek,Edlová, Tereza,Oeser, Petr,Tobrman, Tomá?
, p. 4958 - 4967 (2021)
The present work describes the preparation of halohydrins from 2-halocyclobutanones by means of reactions with Grignard reagents at ?78 °C. We discovered that the prepared cyclobutanols underwent a thermal ring-opening reaction. Depending on the structure of the starting cyclobutanol, different products were formed. More specifically, 1-substituted 2-bromocyclobutan-1-ol was found to open to γ-substituted butyrophenones. A novel 1,3-dihydro-2H-inden-2-ylidene derivative was obtained for indene-derived cyclobutanols. Based on the outcomes of the performed experiments, a mechanism for the ring-opening of cyclobutanols can be proposed.
Hydroxyapatite-supported palladium nanoclusters: A highly active heterogeneous catalyst for selective oxidation of alcohols by use of molecular oxygen
Mori, Kohsuke,Hara, Takayoshi,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 10657 - 10666 (2004)
Treatment of a stoichiometric hydroxyapatite (HAP), Ca10(PO 4)6(OH)2, with PdCl2(PhCN) 2 gives a new type of palladium-grafted hydroxyapatite. Analysis by means of powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX), IR, and Pd K-edge X-ray absorption fine structure (XAFS) proves that a monomeric PdCl2 species is chemisorbed on the HAP surface, which is readily transformed into Pd nanoclusters with a narrow size distribution in the presence of alcohol. Nanoclustered Pd 0 species can effectively promote the alcohol oxidation under an atmospheric O2 pressure, giving a remarkably high turnover number (TON) of up to 236 000 with an excellent turnover frequency (TOF) of approximately 9800 h-1 for a 250-mmol-scale oxidation of 1-phenylethanol under solvent-free conditions. In addition to advantages such as a simple workup procedure and the ability to recycle the catalyst, the present Pd catalyst does not require additives to complete the catalytic cycle. The diameters of the generated Pd nanoclusters can be controlled upon acting on the alcohol substrates used. Oxidation of alcohols is proposed to occur primarily on low-coordination sites within a regular arrangement of the Pd nanocluster by performing calculations on the palladium crystallites.
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Rothgery et al.
, p. 4971 (1975)
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Posner,Chapdelaine
, p. 555 (1977)
Reactivity of aqueous Fe(IV) in hydride and hydrogen atom transfer reactions
Pestovsky, Oleg,Bakac, Andreja
, p. 13757 - 13764 (2004)
Oxidation of cyclobutanol by aqueous Fe(IV) generates cyclobutanone in ～70% yield. In addition to this two-electron process, a smaller fraction of the reaction takes place by a one-electron process, believed to yield ring-opened products. A series of aliphatic alcohols, aldehydes, and ethers also react in parallel hydrogen atom and hydride transfer reactions, but acetone and acetonitrile react by hydrogen atom transfer only. Precise rate constants for each pathway for a number of substrates were obtained from a combination of detailed kinetics and product studies and kinetic simulations. Solvent kinetic isotope effect for the self-decay of Fe(IV), kH2O/kD2O, = 2.8, is consistent with hydrogen atom abstraction from water.
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Hanack,M. et al.
, p. 4613 - 4615 (1968)
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In search of α-eliminations of carbon induced by sixteen electron iron: photolysis and thermolysis of derivatives of phenyl substituted cyclobutanes and cyclopropanes
Trace, Rhonda,Jones, W. M.
, p. 103 - 114 (1989)
Photolysis of dicarbonyl(ε5-cyclopentadienyl)(1-phenylcyclobutane-1-carbonyl)iron is proposed to give the hydride complex Ph(cyclobutenyl)Fe(Cp)(CO)H which dissociates to 1-phenylcyclobutene and FpH (Fp = ε5-cyclopentadienyldicarbonyliron).The FpH complex can oxidatively add to the sixteen electron acyl or ? complexes (Ph(cyclobutyl)-C(O)FeCp(CO) and Ph(cyclobutyl)FeCp(CO) respectively) to produce phenylcyclobutane and 1-phenylcyclobutane carboxaldehyde.Photolysis of dicarbonyl(ε5-cyclopentadienyl)(1-phenylcyclopropyl-1-carbonyl)iron gives a ? complex with no further reaction.Substitution of CO with PPh3 and thermolysis producrally substituted ?-allyl complex.In neither the cyclobutyl nor the cyclopropyl case did the reactions give isolable carbene complexes; apparently the phenyl substituent does not provide adequate stabilization of the carbene complex to allow its detection or isolation.
PYRANO[4,3-B]L NDOLE DERIVATIVES AS ALPHA-1 -ANTITRYPSIN MODULATORS FOR TREATING ALPHA-1 -ANTITRYPSIN DEFICIENCY (AATD)
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Paragraph 00128-00129; 00216, (2021/10/11)
Pyrano[4,3-b]indole derivatives as alpha-1-antitrypsin modulators for treating alpha-1-antitrypsin deficiency (AATD)
Synthesis method of cyclobutanone
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Paragraph 0015; 0019; 0020, (2020/06/02)
The invention provides a synthesis method of cyclobutanone. The method taking cyclopropanecarboxylic acid as a raw material comprises the following steps: reducing the raw material into cyclopropylmethanol, rearranging the cyclopropylmethanol under an acidic condition to obtain cyclobutanol, and carrying out TEMPO oxidation to obtain cyclobutanone. The method has the following advantages: the rawmaterials are cheap, the operation is simple, the total yield is high, and the product with the purity of 99% can be obtained through simple post-treatment. The method produces less three wastes and is suitable for large-scale production.
