654-42-2Relevant academic research and scientific papers
Sensitive electrochemical measurement of hydroxyl radical generation induced by the xanthine-xanthine oxidase system
Tatsumi, Hirosuke,Tsuchiya, Yui,Sakamoto, Koichi
, p. 22 - 27 (2014)
A sensitive electrochemical measurement system for hydroxyl radical (OH) was developed using enzyme-catalyzed signal amplification. In the presence of 2,6-xylenol as a trapping agent, glucose as a substrate, and pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) as a catalyst, the amperometric signal of the trapping adduct 2,6-dimethylhydroquinone (DMHQ) produced by the hydroxylation of 2,6-xylenol was able to be amplified and detected sensitively. The limit of detection (signal/noise [S/N] = 3) for DMHQ was 1 nM. There was no significant interference from urate and other oxidizable compounds in the reaction mixture at the applied potential of 0 V versus Ag/AgCl. This method was employed to observe the OH generation induced by the xanthine-xanthine oxidase (XO) system. The reaction rates of the DMHQ production induced from the xanthine-XO system in the presence and absence of various Fe(III) complexes and proteins were compared. Those with a free coordination site on the Fe atom effectively enhanced the OH generation.
Effect of different carboxylic acids on the aromatic hydroxylation with H2O2 in the presence of an iron aminopyridine complex
Tkachenko, Nikolay V.,Lyakin, Oleg Y.,Zima, Alexandra M.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 130 - 134 (2018)
In this contribution, the effect of the structure of the catalytic additive – carboxylic acid – on the catalytic performance of the iron based catalyst [(PDP)Fe(OTf)2], 2 (PDP = N,N′-bis(2-pyridylmethyl)-(S,S)-2,2′-bipyrrolidine) in the selecti
Iron-catalyzed arene C-H hydroxylation
Cheng, Lu,Wang, Huihui,Cai, Hengrui,Zhang, Jie,Gong, Xu,Han, Wei
, p. 77 - 81 (2021/10/05)
The sustainable, undirected, and selective catalytic hydroxylation of arenes remains an ongoing research challenge because of the relative inertness of aryl carbon-hydrogen bonds, the higher reactivity of the phenolic products leading to over-oxidized by-products, and the frequently insufficient regioselectivity. We report that iron coordinated by a bioinspired L-cystine-derived ligand can catalyze undirected arene carbon-hydrogen hydroxylation with hydrogen peroxide as the terminal oxidant. The reaction is distinguished by its broad substrate scope, excellent selectivity, and good yields, and it showcases compatibility with oxidation-sensitive functional groups, such as alcohols, polyphenols, aldehydes, and even a boronic acid. This method is well suited for the synthesis of polyphenols through multiple carbon-hydrogen hydroxylations, as well as the late-stage functionalization of natural products and drug molecules.
SPERMINE PRO-DRUGS
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Paragraph 0025; 0060-0062, (2021/01/26)
Disclosed herein are novel spermine prodrugs and methods of use for treating subjects exhibiting symptoms of a low spermine disorder. Also disclosed are methods of synthesizing spermine prodrugs. Compositions containing spermine prodrugs are also disclosed.
Determining Proton-Coupled Standard Potentials and X-H Bond Dissociation Free Energies in Nonaqueous Solvents Using Open-Circuit Potential Measurements
Agarwal, Rishi G.,Mayer, James M.,Wise, Catherine F.
supporting information, p. 10681 - 10691 (2020/07/06)
Proton-coupled electron transfer (PCET) reactions are increasingly being studied in nonaqueous conditions, where the thermochemistry of PCET substrates is largely unknown. Herein, we report a method to obtain electrochemical standard potentials and calculate the corresponding bond dissociation free energies (BDFEs) of stable PCET reagents in nonaqueous solvents, using open-circuit potential (OCP) measurements. With this method, we measure PCET thermochemistry in acetonitrile and tetrahydrofuran for substrates with O-H and N-H bonds that undergo 1e-/1H+ and 2e-/2H+ redox processes. We also report corrected thermochemical values for the 1/2H2(g)/H?1M and H+/H? (CG) couples in several organic solvents. For 2e-/2H+ couples, OCP measurements provide the multielectron/multiproton standard potential and the average of the two X-H BDFEs. In contrast to traditional approaches for calculating BDFEs from electrochemical measurements, the OCP method directly measures the overall PCET reaction thermodynamics and avoids the need for a pKa scale in the solvent of interest. Consequently, the OCP approach yields more accurate thermochemical values and should be general to any solvent mixture compatible with electrochemical measurements. The longer time scale of OCP measurements enables accurate thermochemical measurements for redox couples with irreversible or distorted electrochemical responses by cyclic voltammetry, provided the PCET reaction is chemically reversible. Recommendations for successful OCP measurements and limitations of the approach are discussed, including the current inability to measure processes involving C-H bonds. As a straightforward and robust technique to determine nonaqueous PCET thermochemistry, these OCP measurements will be broadly valuable, with applications ranging from fundamental reactivity studies to device development.
1-Methyl-1,4-cyclohexadiene as a Traceless Reducing Agent for the Synthesis of Catechols and Hydroquinones
Baschieri, Andrea,Amorati, Riccardo,Valgimigli, Luca,Sambri, Letizia
, p. 13655 - 13664 (2019/10/28)
Pro-aromatic and volatile 1-methyl-1,4-cyclohexadiene (MeCHD) was used for the first time as a valid H-atom source in an innovative method to reduce ortho or para quinones to obtain the corresponding catechols and hydroquinones in good to excellent yields. Notably, the excess of MeCHD and the toluene formed as the oxidation product can be easily removed by evaporation. In some cases, trifluoroacetic acid as a catalyst was added to obtain the desired products. The reaction proceeds in air and under mild conditions, without metal catalysts and sulfur derivatives, resulting in an excellent and competitive method to reduce quinones. The mechanism is attributed to a radical reaction triggered by a hydrogen atom transfer from MeCHD to quinones, or, in the presence of trifluoroacetic acid, to a hydride transfer process.
The synthesis and evaluation of thymoquinone analogues as anti-ovarian cancer and antimalarial agents
Johnson-Ajinwo, Okiemute Rosa,Ullah, Imran,Mbye, Haddijatou,Richardson, Alan,Horrocks, Paul,Li, Wen-Wu
supporting information, p. 1219 - 1222 (2018/03/12)
Thymoquinone (TQ), 2-isopropyl-5-methyl-1,4-benzoquinone, a natural product isolated from Nigella sativa L., has previously been demonstrated to exhibit antiproliferative activity in vitro against a range of cancers as well as the human malarial parasite Plasmodium falciparum. We describe here the synthesis of a series of analogues of TQ that explore the potential for nitrogen-substitution to this scaffold, or reduction to a hydroquinone scaffold, in increasing the potency of this antiproliferative activity against ovarian cancer cell lines and P. falciparum. In addition, alkyl or halogen-substituted analogues were commercially sourced and tested in parallel. Several TQ analogues with improved potency against ovarian cancer cells and P. falciparum were found, although this increase is suggested to be moderate. Key aspects of the structure activity relationship that could be further explored are highlighted.
Pd0-PyPPh2@porous organic polymer: Efficient heterogeneous nanoparticle catalyst for dehydrogenation of 3-methyl-2-cyclohexen-1-one without extra oxidants and hydrogen acceptors
Chen, Xingkun,Wang, Wenlong,Zhu, Hejun,Yang, Wenshao,Ding, Yunjie
, p. 49 - 56 (2018/07/24)
In this contribution, we have developed an efficient and recyclable porous organic polymer (POP) supported Pd nanoparticle catalyst (Pd°-PyPPh2@POP) for dehydrogenation of 3-methyl-2-cyclohexen-1-one. This heterogeneous catalytic system represents a totally clean process without using any extra oxidant and hydrogen acceptors. The SEM-EDS mapping images of the Pd°-PyPPh2@POP catalyst reveal the highly uniformly dispersed character of C, Pd, P and N elements. The coordination bonds between Pd nanoparticle and exposed P atom as well as N atom on the surface of PyPPh2@POP polymer are confirmed by means of solid-state 31P NMR and XPS. Importantly, both P atom and pyridyl ring on the PyPPh2@POP polymer are themselves used as solid base over the Pd°-PyPPh2@POP catalyst, leading to a catalytic conversion of 88.2% even without the employment of inorganic base additives (K2CO3). Our results have provided a strategy for designing highly active bifunctional POP supported nanoparticle catalysts.
Catalytic Electrophilic Alkylation of p-Quinones through a Redox Chain Reaction
Xu, Xiao-Long,Li, Zhi
supporting information, p. 8196 - 8200 (2017/06/30)
Allylation and benzylation of p-quinones was achieved through an unusual redox chain reaction. Mechanistic studies suggest that the existence of trace hydroquinone initiates a redox chain reaction that consists of a Lewis acid catalyzed Friedel–Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. The addition of Hantzsch ester as an initiator improves the efficiency of the reaction.
Catalytic activity of Fe-porphyrins grafted on multiwalled carbon nanotubes in the heterogeneous oxidation of sulfides and degradation of phenols in water
Rayati, Saeed,Nejabat, Fatemeh
, p. 967 - 974 (2017/09/26)
A biomimetic heterogeneous catalyst was prepared by immobilization of meso-tetrakis(4-carboxyphenyl)porphyrinatoiron(III) chloride (Fe(TCPP)Cl) on multiwalled carbon nanotubes (MWCNTs). The anchored catalyst was characterized by transmission electron microscopy, powder X-ray diffraction, ultraviolet–visible, and Fourier transform infrared spectroscopy. The amount of Fe-porphyrin loaded on the nanotubes was estimated by atomic absorption spectroscopy The thermogravimetric analysis demonstrated that the catalyst was thermally stable up to almost 350 °C, exhibiting high thermal stability. Oxidation of sulfides and phenols with urea hydrogen peroxide (UHP) in water was efficiently enhanced with excellent selectivity under the influence of [Fe(TCPP)Cl@MWCNT]. The title heterogeneous catalytic system facilitates a greener reaction because the reaction solvent is water and UHP is used as a safe oxidant.
