6390-69-8Relevant articles and documents
Copper(II) complexes of piperazine-derived tetradentate ligands and their chiral diazabicyclic analogues for catalytic phenol oxidative C-C coupling
Castillo, Ivan,Pérez, Viridiana,Monsalvo, Iván,Demare,Regla, Ignacio
, p. 1 - 4 (2013)
Reaction of the chiral ligands (1S,4S)-2,5-bis(6-methylpyridyl)- diazabicyclo[2.2.1]heptane (L1) and (1S,4S)-2,5-bis(1-methyl-2- methylbenzimidazolyl)-diazabicyclo[2.2.1]heptane (L2) with CuCl 2 results in the hydroxo-bridged dicopper complexes [(L 1)Cu2(μ-OH)(H2O)Cl3] (3), and [(L2)Cu2(μ-OH)(H2O)Cl3] (4). Both chiral complexes were characterized spectroscopically, and 3 in the solid state by X-ray crystallography, confirming they are structurally related to their previously reported copper acetate analogues (1 and 2) due to their hydroxo-bridged bimetallic core. The achiral ligand analogues N,N′-bis(2-picolyl)piperazine (L3) and N,N′-bis(1-methyl- 2-methylbenzimidazolyl)piperazine (L4) were employed to obtain the corresponding complexes with CuCl2, affording the chloro-bridged [(L3)(CuCl)2(μ-Cl)2]n (5) and [(L4)(CuCl)2(μ-Cl)2] (6), neither of which features a bridging hydroxo ligand; instead, complex 5 was structurally characterized as a coordination polymer. The acetate-derived complexes 1 and 2 are active in oxidative C-C coupling of 2,4-di-tert-butylphenol, while 3 and 4 have low activity; the achiral complexes 5 and 6, lacking a bridging hydroxo ligand, are inactive in this reaction.
Unprecedented direct cupric-superoxo conversion to a bis-μ-oxo dicopper(III) complex and resulting oxidative activity
Quist, David A.,Ehudin, Melanie A.,Karlin, Kenneth D.
, p. 155 - 161 (2019)
Investigations of small molecule copper-dioxygen chemistry can and have provided fundamental insights into enzymatic processes (e.g., copper metalloenzyme dioxygen binding geometries and their associated spectroscopy and substrate reactivity). Strategically designing copper-binding ligands has allowed for insight into properties that favor specific (di)copper-dioxygen species. Herein, the tetradentate tripodal TMPA-based ligand (TMPA = tris((2-pyridyl)methyl)amine) possessing a methoxy moiety in the 6-pyridyl position on one arm (OCH3TMPA) was investigated. This system allows for a trigonal bipyramidal copper(II) geometry as shown by the UV–vis and EPR spectra of the cupric complex [(OCH3TMPA)CuII(OH2)](ClO4)2. Cyclic voltammetry experiments determined the reduction potential of this copper(II) species to be ?0.35 V vs. Fc+/0 in acetonitrile, similar to other TMPA-derivatives bearing sterically bulky 6-pyridyl substituents. The copper-dioxygen reactivity is also analogous to these TMPA-derivatives, affording a bis-μ-oxo dicopper(III) complex, [{(OCH3TMPA)CuIII}2(O2?)2]2+, upon oxygenation of the copper(I) complex [(OCH3TMPA)CuI](B(C6F5)4) at cryogenic temperatures in 2-methyltetrahydrofuran. This highly reactive intermediate is capable of oxidizing phenolic substrates through a net hydrogen atom abstraction. However, after bubbling of the precursor copper(I) complex with dioxygen at very low temperatures (?135 °C), a cupric superoxide species, [(OCH3TMPA)CuII(O2[rad]?)]+, is initially formed before slowly converting to [{(OCH3TMPA)CuIII}2(O2?)2]2+. This appears to be the first instance of the direct conversion of a cupric superoxide to a bis-μ-oxo dicopper(III) species in copper(I)-dioxygen chemistry.
Activation of a high-valent manganese-oxo complex by a nonmetallic lewis acid
Baglia, Regina A.,Duerr, Maximilian,Ivanovic-Burmazovic, Ivana,Goldberg, David P.
, p. 5893 - 5895 (2014)
The reaction of a manganese(V)-oxo porphyrinoid complex with the Lewis acid B(C6F5)3 leads to reversible stabilization of the valence tautomer MnIV(O)(π-radical cation). The latter complex, in combination with B(C6F5)3, reacts with ArO-H substrates via formal hydrogen-atom transfer and exhibits dramatically increased reaction rates over the MnV(O) starting material.
Influence of ligand architecture on oxidation reactions by high-valent nonheme manganese oxo complexes using water as a source of oxygen
Barman, Prasenjit,Vardhaman, Anil Kumar,Martin, Bodo,W?rner, Svenja J.,Sastri, Chivukula V.,Comba, Peter
, p. 2095 - 2099 (2015)
Mononuclear nonheme MnIV=O complexes with two isomers of a bispidine ligand have been synthesized and characterized by various spectroscopies and density functional theory (DFT). The MnIV=O complexes show reactivity in oxidation reactions (hydrogen-atom abstraction and sulfoxidation). Interestingly, one of the isomers (L1) is significantly more reactive than the other (L2), while in the corresponding FeIV=O based oxidation reactions the L2-based system was previously found to be more reactive than the L1-based catalyst. This inversion of reactivities is discussed on the basis of DFT and molecular mechanics (MM) model calculations, which indicate that the order of reactivities are primarily due to a switch of reaction channels (σ versus π) and concomitant steric effects.
Direct Resonance Raman Characterization of a Peroxynitrito Copper Complex Generated from O2 and NO and Mechanistic Insights into Metal-Mediated Peroxynitrite Decomposition
Liu, Jeffrey J.,Siegler, Maxime A.,Karlin, Kenneth D.,Mo?nne-Loccoz, Pierre
, p. 10936 - 10940 (2019)
We report the formation of a new copper peroxynitrite (PN) complex [CuII(TMG3tren)(κ1-OONO)]+ (PN1) from the reaction of [CuII(TMG3tren)(O2.?)]+ (1) with NO.(g) at ?125 °C. The first resonance Raman spectroscopic characterization of such a metal-bound PN moiety supports a cis κ1-(?OONO) geometry. PN1 transforms thermally into an isomeric form (PN2) with κ2-O,O′-(?OONO) coordination, which undergoes O?O bond homolysis to generate a putative cupryl (LCuII?O.) intermediate and NO2.. These transient species do not recombine to give a nitrato (NO3?) product but instead proceed to effect oxidative chemistry and formation of a CuII–nitrito (NO2?) complex (2).
Cu(II)-mediated phenol oxygenation: Chemical evidence implicates a unique role of the enzyme active site in promoting the chemically difficult tyrosine monooxygenation in TPQ cofactor biogenesis of copper amine oxidases
Fu, Zhengjiang,Xu, Feng,Cai, Hu
, p. 31 - 38 (2015)
Cu(II)-mediated autoxidations of 4-tert-butylphenol under various conditions was studied, the data confirmed imidazole is the best ligand to promote phenol oxygenation. The same reaction of 2,4-di-tert-butylphenol proceeded much more quickly to lead nearly exclusively to oxidative coupling rather than oxygenation under high pressure O2. These results suggested that Cu(II)-catalyzed phenol autoxidation by activating O2 and phenol in terms of a phenoxy radical (ArO.)-Cu(II)-superoxide ternary complex, whereas selectivity between oxygenation and coupling depends mainly on the electronic structure of ArO.. It is appeared that CuAOs could achieve stoichiometric tyrosine monooxygenation by modulating the redox potential of Cu(II) and stabilizing the ternary complex through protein conformational adjustment.
BOX ligands in biomimetic copper-mediated dioxygen activation: A hemocyanin model
Walli, Adam,Dechert, Sebastian,Bauer, Matthias,Demeshko, Serhiy,Meyer, Franc
, p. 4660 - 4676 (2014)
The μ-η2:η2-peroxodicopper(II) core found in the oxy forms of the active sites of type III dicopper proteins have been a key target for bioinorganic model studies. Here, it is shown that simple bis(oxazoline)s (BOXs), which are classified among the so-called "privileged ligands", provide a suitable scaffold for supporting such biomimetic copper/dioxygen chemistry. Three derivatives R,HBOX-Me2 (R = H, Me, tBu) with different backbone substituents have been used. Their bis(oxazoline)-copper(I) complexes bind dioxygen to yield biomimetic μ-η2:η2-peroxodicopper(II) species. O2 can be reversibly released upon an increase in temperature. Their formation kinetics have been studied under cryo-stopped-flow conditions for the tBu derivative, giving activation parameters ΔH?on = (2.27 ± 0.18) kcal mol-1, ΔS?on = (-46.3 ± 0.8) cal K-1 mol-1 for the binding event and ΔH?off = (11.7 ± 1.9) kcal mol-1, ΔS?off = (-16.1 ± 8.2) cal K-1 mol-1 for the release of O2, as well as thermodynamic parameters ΔH = (-10.0 ± 1.7) kcal mol-1 and ΔS = (-32.7 ± 7.4) cal K-1 mol-1 for this equilibrium. The μ-η2:η2-peroxodicopper(II) complexes have been isolated as surprisingly stable solids and investigated in depth by a variety of methods, both in solution and in the solid state. Resonance Raman spectroscopy revealed a characteristic isotope-sensitive stretch τilde {nu}$O-O = 731-742 cm-1 (Δ[18O2] ≈ -39 cm-1) and an intense feature around 280 cm-1 diagnostic for the fundamental symmetric Cu2O2 core vibration. A slight butterfly-shape of the Cu2O2 core has been derived from EXAFS data and DFT calculations. SQUID magnetic data evidenced strong antiferromagnetic coupled CuII2 (-2J ≥ 1000 cm-1). Thermal degradation in solution yields bis(hydroxo)-bridged [(tBu,HBOX-Me2)(L)Cu(OH)]2(PF6)2 (L = H2O, MeCN or THF); whereas in the case of H,HBOX-Me2, ligand oxygenation has been detected. Preliminary reactivity studies with the substrate 2,4-di-tert-butylphenol indicate the formation of the C-C coupling product 3,3,5,5-tetra-tert-butyl-2,2-biphenol, whereas ortho-hydroxylation was not observed. The copper(I) complex [(tBu,HBOX-Me2)Cu(MeCN)]PF6 as well as two dicopper(II) complexes [(L)(tBu,HBOX-Me2)Cu(OH)]2(PF6)2 have been characterised by single-crystal X-ray diffraction. Considering the vast number of known BOX derivatives, a rich and versatile Cu/O2 chemistry based on this platform is anticipated.
Purification method of 3, 3 ', 5, 5'-tetrasubstituent-2, 2 '-biphenol
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Paragraph 0077-0084; 0093-0108, (2021/06/23)
The invention relates to the technical field of organic chemical industry, in particular to a purification method of 3, 3 ', 5, 5'-tetrasubstituent-2, 2 '-biphenol, which comprises the following steps: A) stirring and mixing 3, 3', 5, 5 '-tetrasubstituent-2, 2'-biphenol and a purifying agent to obtain a mixed material; wherein the purifying agent comprises one or more of liquid organic alcohol compounds; and B) carrying out solid-liquid separation on the mixed material, and drying the obtained solid product to obtain the purified 3, 3 ', 5, 5'-tetrasubstituent-2, 2 '-biphenol. The purification of 3, 3 ', 5, 5'-tetrasubstituent-2, 2 '-biphenol is realized under specific process steps by adopting the purifying agent with specific composition, and the method is simple in process, mild in condition, recyclable in purifying agent, low in material consumption and energy consumption, high in overall operability, capable of effectively improving the purity and appearance of the product and high in yield of the purified product.
Phenol Reduces Nitrite to NO at Copper(II): Role of a Proton-Responsive Outer Coordination Sphere in Phenol Oxidation
Bertke, Jeffery A.,Kundu, Subrata,Mondal, Aditesh,Reddy, Kiran P.
supporting information, (2020/02/04)
In the view of physiological significance, the transition-metal-mediated routes for nitrite (NO2-) to nitric oxide (NO) conversion and phenol oxidation are of prime importance. Probing the reactivity of substituted phenols toward the nitritocopper(II) cryptate complex [mC]Cu(κ2-O2N)(ClO4) (1a), this report illustrates NO release from nitrite at copper(II) following a proton-coupled electron transfer (PCET) pathway. Moreover, a different protonated state of 1a with a proton hosted in the outer coordination sphere, [mCH]Cu(κ2-O2N)(ClO4)2 (3), also reacts with substituted phenols via primary electron transfer from the phenol. Intriguingly, the alternative mechanism operative because of the presence of a proton at the remote site in 3 facilitates an unusual anaerobic pathway for phenol nitration.
Method for synthesizing bisphosphite
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Paragraph 0069; 0071; 0075; 0076, (2020/06/02)
The invention provides a method for synthesizing bisphosphite, comprising the following steps: 1) carrying out an oxidative coupling reaction on phenol as shown in a general formula (I) under the action of a supported copper-based catalyst to obtain diphenol as shown in a general formula (II); 2) carrying out a reaction between the diphenol shown in the general formula (III) and phosphorus trichloride to obtain biphenoxy phosphine chloride as shown in the general formula (IV); and 3) carrying out a reaction between the diphenol represented by the general formula (II) and biphenyl oxyphosphinechloride as shown in the general formula (IV) to obtain bisphosphite as shown in the general formula (V). In the general formulas (I), (II), (III), (IV) and (V), X1, X2, Y1, Y2, Z1 and Z2 are independently hydrogen, C1-6 alkyl or C1-6 alkoxy.
