4640-29-3Relevant academic research and scientific papers
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.
Heterogeneous Nitrogen-doped Graphene Catalysed HOO? Generation via a Non-radical Mechanism for Base-free Dakin Reaction
Sun, Wei,Gao, Lingfeng,Sun, Xu,Yang, Hua,Zheng, Gengxiu
supporting information, p. 5210 - 5216 (2019/11/03)
A heterogeneous nitrogen-doped graphene catalytic pathway for H2O2 activation to generate alkaline hydrogen peroxide (HOO?) through a non-radical mechanism was reported. Remarkably, the heterogeneous catalytic procedure has been used for the evergreen and environmentally Dakin reaction without using any transition metals, homogeneous bases, ligands, additives or promoters, completely. The study of catalyst structure and catalytic activities indicate that the most active sites are created by the graphitic N atoms at zig-zag edges of the sheets. In addition, N as dopant element changes the reactivity of the neighbour C atoms, and leads to the formation of carbon-hydroperoxide (C?(HOOH)) and C?O* (C?O?) transition state species on the graphene surface in catalytic the reaction. (Figure presented.).
The design, synthesis, and evaluation of organ-specific iron chelators
Bergeron, Raymond J.,Wiegand, Jan,McManis, James S.,Bharti, Neelam
, p. 7032 - 7043 (2007/10/03)
A series of iron chelators, three (S)-4,5-dihydro-2-(2-hydroxyphenyl)-4- methyl-4-thiazolecarboxylic acid (DADFT) and three (S)-4,5-dihydro-2-(2- hydroxyphenyl)-4-thiazolecarboxylic acid (DADMDFT) analogues are synthesized and assessed for their lipophilicity (log Papp), iron-clearing efficiency (ICE) in rodents and iron-loaded primates (Cebus apella), toxicity in rodents, and organ distribution in rodents. The results lead to a number of generalizations useful in chelator design strategies. In rodents, while log Papp is a good predictor of a chelator's ICE, chelator liver concentration is a better tool. In primates, log Papp is a good predictor of ICE, but only when comparing structurally very similar chelators. There is a profound difference in toxicity between the DADMDFT and DADFT series: DADMDFTs are less toxic. Within the DADFT family of ligands, the more lipophilic ligands are generally more toxic. Lipophilicity can have a profound effect on ligand organ distribution, and ligands can thus be targeted to organs compromised in iron overload disease, for example, the heart.
Photochemistry of substituted 4-halogenophenols: Effect of a CN substituent
Bonnichon, Florent,Grabner, Gottfried,Guyot, Ghislain,Richard, Claire
, p. 1203 - 1210 (2007/10/03)
The photochemistry of 5-chloro-2-hydroxybenzonitrile 1 was studied in aqueous solution using transient absorption spectroscopy and product analysis. The triplet carbene 3-cyano-4-oxocyclohexa-2,5-dienylidene 2 (λmax/nm 385, 368) was successfully detected and identified on the basis of its characteristic reactivity. This transient species is converted into cyanobenzo-1,4-quinone-O-oxide (λmax/nm 470) by reaction with oxygen and is reduced into 2-cyanophenoxyl radical (λmax/nm 402, 387) by propan-2-ol. The product studies confirm the intermediary formation of carbene 2. 2,5-Dihydroxybenzonitrile 3 and the biphenyls 4 and 5 are primary photoproducts in deoxygenated solutions whereas 2-hydroxybenzonitrile 9 and 5-bromo-2-hydroxybenzonitrile 10 are cleanly produced upon addition of propan-2-ol (0.13 M) and bromide ions (10-2 M), respectively. In oxygen-saturated solutions, cyanobenzo-1,4-quinone 8 is the main photoproduct. The quantum yield of carbene formation (0.062) is reduced by 40% in the presence of oxygen and is increased up to a value of 0.20 upon addition of bromide or iodide ions. These results can be interpreted in terms of triplet quenching and heavy-atom enhancement and support the assumption that the carbene 2 is formed from the triplet excited state of 1; this assumption is supported by a detailed study of the phototransformation of 1 in ethanol. Mono- and biphotonic formations of solvated electrons and 4-chloro-2-cyanophenoxyl radicals (λmax/nm 427, 408) are also observed from neutral 1. The effects of CN substitution can be traced to deprotonation of the lowest excited singlet state on the one hand (pK* = 0.12 ± 0.04) and to an increase of the triplet lifetime on the other.
Isolation of bright blue fluorescent substances from sonochemical hydroxylation of methyl p-cyanobenzoate
Yamada, Sachiko,Hokari, Hajime,Akasaka, Shinji,Iwamura, Michiko
, p. 197 - 198 (2007/10/03)
Sonochemical hydroxylation of methyl p-cyanobenzoate (1a) in water gave a bright blue fluorescence, which are mainly ascribed to three new fluorescent compounds, 3-hydroxy, 2,3- and 2,5-dihydroxy derivatives of 1a. Other benzenes substituted with electron-withdrawing groups also gave similar fluorescence from their hydroxylated derivatives. Among the fluorescence substances, methyl 2,5-dihydroxybenzoate was supposed to be applicable for a fluorescent chemosensor.
TEMPLATE HOUBEN-HOESCH REACTION ON METAL PHENOLATES. SYNTHESIS OF AROMATIC KETONES, NITRILES AND AMIDES. CRYSTAL STRUCTURE OF DICHLORO-BORON
Bigi, Franca,Maggi, Raimondo,Sartori, Giovanni,Casnati, Giuseppe,Bocelli, Gabriele
, p. 283 - 289 (2007/10/02)
The crystal structure of dichloro-boron (6dx) establishes for the first time the coordination mechanism of the ortho-selective reaction of metal phenolates and nitriles.Crystal data: chemical formula C9H7BCl5NO2; a = 11.743(2), b = 13.390(2), c = 8.765(3) Angstroem, β = 99.71(2) deg; space group P21/n.Variously substituted aromatic ketones, nitriles and amides have been obtained in a "one-pot" reaction.
Synthesis of Substituted Phenazines from Benzofurazanoxid and Hydroquinones
Roemer, A.,Sammet, M.
, p. 866 - 872 (2007/10/02)
The sterical course of the formation of substituted phenazines from benzofurazanoxid and hydroquinone derivatives was investigated.The additional functional group of the hydroquinone determines the substitution pattern and the product ratio of the phenazines formed. - Key words: Phenazine, Synthese, Hydrochinone
THE HYDROCYANATION OF FREE AND POLYMER-BOUND BENZOQUINONE
Perry, Gregory J.,Sutherland, Maurice D.
, p. 1471 - 1476 (2007/10/02)
The polimer-bound quinone 2 has been prepared and used in column form with organic solvents for the convenient preparation of other quinones.In contrast to the solution reaction hydrocyanation of this quinone by the Thiele-Meisenheimer reaction did not yield a useful proportion of polymer-bound dicyanohydroquinone but instead gave a mixture of products including much monocyanohydroquinone.Helferich and Bodenbender's 2,3-dicyanocyclohexan-1,4-dione is in fact wholly the di-enol and is a likely intermediate in the hydrocyanation of benzoquinone, being oxidised by the latter to 2,3-dicyanocyclohex-2-ene-1,4-dione which tautomerises to the observed product, 2,3-dicyanohydroquinone.A lower accessibility to polymer-bound reactants as compared with those in solution is implied by these results.
