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1953-54-4Relevant academic research and scientific papers
Gut bacteria-derived 5-hydroxyindole is a potent stimulant of intestinal motility via its action on L-type calcium channels
Waclawiková, Barbora,Bullock, Amber,Schwalbe, Markus,Aranzamendi, Carmen,Nelemans, Sieger A.,van Dijk, Gertjan,El Aidy, Sahar
, (2021/02/22)
Microbial conversion of dietary or drug substrates into small bioactive molecules represents a regulatory mechanism by which the gut microbiota alters intestinal physiology. Here, we show that a wide variety of gut bacteria can metabolize the dietary supplement and antidepressant 5-hydroxytryptophan (5-HTP) to 5-hydroxyindole (5-HI) via the tryptophanase (TnaA) enzyme. Oral administration of 5-HTP results in detection of 5-HI in fecal samples of healthy volunteers with interindividual variation. The production of 5-HI is inhibited upon pH reduction in in vitro studies. When administered orally in rats, 5-HI significantly accelerates the total gut transit time (TGTT). Deciphering the underlying mechanisms of action reveals that 5-HI accelerates gut contractility via activation of L-type calcium channels located on the colonic smooth muscle cells. Moreover, 5-HI stimulation of a cell line model of intestinal enterochromaffin cells results in significant increase in serotonin production. Together, our findings support a role for bacterial metabolism in altering gut motility and lay the foundation for microbiota-targeted interventions.
Visible-light-promoted aerobic oxidative hydroxylation of arylboronic acids in water by hydrophilic organic semiconductor
Yu, Kunyi,Zhang, Hanjie,Sheng, Yuqiang,Zhu, Yongfa
supporting information, (2020/06/23)
A green and sustainable catalytic system was developed based on perylenediimide (PDI) organic semiconductor for the aerobic oxidative hydroxylation of arylboronic acids in aqueous solution with visible light. By using PDI-SN, a hydrophilic organic semiconductor, which can activate oxygen to produce superoxide radicals in aqueous solution, this reaction proceeds under ambient conditions: water as the solvent and air as the oxidant, giving various phenols as products with high yields. In contrast to methods using organic solvents, this novel process has the potential of green industrial application.
Superhydrophobic nickel/carbon core-shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles
Duan, Zhiying,Liu, Fangfang,Pang, Shaofeng,Su, Qiong,Wang, Yanbin,Xie, Xin,Zhang, Ping,Zhang, Yujing,Zhou, Feng
, p. 1996 - 2010 (2020/04/07)
In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step. Nevertheless, how to effectively reduce the possible effects of water on the catalyst by removal of the by-product water, and to further introduce water as the solvent based on green chemistry are still challenges. Since the structures and properties of carbon nanocomposites are easily modified by controllable construction, a one step pyrolysis process is used for controllable construction of micro/nano hierarchical carbon nanocomposites with core-shell structures and magnetic separation performance. Using various characterization methods and model reactions the relationship between the structure of Ni?NCFs (nickel-nitrogen-doped carbon frameworks) and catalytic performance was investigated, and the results show that there is a positive correlation between the catalytic performance and hydrophobicity of catalysts. Besides, the possible catalytically active sites, which are formed by the interaction of pyridinic N and graphitic N in the structure of nitrogen-doped graphene with the surfaces of Ni nanoparticles, should be pivotal to achieving the relatively high catalytic performance of materials. Due to its unique structure, the obtained Ni?NCF-700 catalyst with superhydrophobicity shows extraordinary performances toward the hydrogen transfer reaction of nitrobenzene and N-heterocycles in the aqueous state; meanwhile, it was also found that Ni?NCF-700 still retained its excellent catalytic activity and structural integrity after three cycles. Compared with traditional catalytic systems, our catalytic systems offer a highly effective, green and economical alternative for nitrobenzene and N-heterocycle transformation, and may open up a new avenue for simple construction of structure and activity defined carbon nanocomposite heterogeneous catalysts with superhydrophobicity.
Diaryliodonium Salt-Mediated Intramolecular C-N Bond Formation Using Boron-Masking N-Hydroxyamides
Matsumoto, Makoto,Wada, Kohei,Urakawa, Kazuki,Ishikawa, Hayato
supporting information, p. 781 - 785 (2020/02/04)
Intramolecular aromatic C-N bond formation reactions using electron-rich aromatic tethered boron-masking N-hydroxyamide as substrate were realized. These new C-N bond formation reactions involve the in situ generation of a diaryliodonium salt by treatment with hypervalent iodine, deborylation by base treatment, spontaneous N → O acyl migration, cyclization, reductive elimination, elimination of benzoic acid, and tautomerization to indole formation. Hereby, we obtained highly functionalized electron-rich indoles and quinoline in practical yields.
A scalable and green one-minute synthesis of substituted phenols
Elumalai, Vijayaragavan,Hansen, J?rn H.
, p. 40582 - 40587 (2020/11/18)
A mild, green and highly efficient protocol was developed for the synthesis of substituted phenols via ipso-hydroxylation of arylboronic acids in ethanol. The method utilizes the combination of aqueous hydrogen peroxide as the oxidant and H2O2/HBr as the reagent under unprecedentedly simple and convenient conditions. A wide range of arylboronic acids were smoothly transformed into substituted phenols in very good to excellent yields without chromatographic purification. The reaction is scalable up to at least 5 grams at room temperature with one-minute reaction time and can be combined in a one-pot sequence with bromination and Pd-catalyzed cross-coupling to generate more diverse, highly substituted phenols.
8-Mercaptoquinoline as a Ligand for Enhancing the Photocatalytic Activity of Pt(II) Coordination Complexes: Reactions and Mechanistic Insights
Casado-Sánchez, Antonio,Uygur, Mustafa,González-Mu?oz, Daniel,Aguilar-Galindo, Fernando,Nova-Fernández, José Luis,Arranz-Plaza, Judith,Díaz-Tendero, Sergio,Cabrera, Silvia,Manche?o, Olga García,Alemán, José
, p. 6437 - 6447 (2019/05/24)
A family of quinoline-platinum(II) complexes as efficient photocatalysts is presented. Their key characteristic is their easy preparation by coordination of the readily available 8-hydroxy- or 8-thio-quinoline ligands, which are well known for their strong chelating ability to different metal ions. In the different photochemical transformations investigated, such as cross-dehydrogenative coupling, oxidation of arylboronic acids, and asymmetric alkylation of aldehydes, 8-mercaptoquinoline-Pt(II) complex proved to be the most general catalyst. Moreover, quenching experiments showed that, contrary to related methods reported in the literature, these complexes followed an oxidative quenching mechanism in all transformations studied. Besides, simulations performed with high-level ab initio methods of the complexes have helped to understand their photocatalytic activity.
back-to-Front Indole Synthesis Using Silver(I) Catalysis: Unexpected C-3 Pyrrole Activation Mode Supported by DFT
Clarke, Aimee K.,Lynam, Jason M.,Taylor, Richard J. K.,Unsworth, William P.
, p. 6844 - 6850 (2018/06/22)
An efficient silver(I)-catalyzed method is reported for the synthesis of substituted indoles, most notably 5-hydroxy-derivatives, via π-acidic alkyne activation. Most methods for the preparation of indoles involve annulation of a benzene precursor, but the method reported herein is unusual in that pyrrole precursors are used. Density Functional Theory (DFT) studies suggest that these reactions proceed via initial activation of the pyrrole C-3 position before undergoing subsequent rearrangement, contradicting the conventional wisdom that pyrroles are more nucleophilic through C-2.
C4 Pictet-Spengler Reactions for the Synthesis of Core Structures in Hyrtiazepine Alkaloids
Abe, Takumi,Haruyama, Tomohiro,Yamada, Koji
, p. 4141 - 4150 (2017/09/13)
The hyrtiazepine alkaloids are a family of bisindole natural products that have the azepinoindole backbone. We developed a biomimetic approach by constructing the azepinoindole core in a one-pot manner through 1,4-diazabicyclo[2.2.2]octane/2,2,2-trifluoroethanol (DABCO/TFE) promoted Pictet-Spengler reaction onto the C-4 position of tryptophan. This strategy allowed the synthesis of common key structures of these families. The key intermediate can be converted into the 3 H -pyrano[2,3- b:5,6- e ′]diindol intermediate present in hyrtimomines A and B, as well as the azepinoindole core present in fargesine..
Preparation method of 5-hydroxyindole
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Paragraph 0052, (2017/05/26)
The invention provides a preparation method of 5-hydroxyindole. The preparation method comprises the following steps of (1) enabling sodium tungstate, sodium dihydrogen phosphate and hexadecyl dimethyl betaine to be subjected to a reaction together so as to prepare phosphotungstate; (2) mixing kaolin with water, performing drying, performing roasting, and adding dehydrated alcohol so as to prepare kaolin sol; (3) compounding the kaolin sol and the phosphotungstate so as to prepare kaolin-loaded phosphotungstate; (4) protecting 1-position of indole with benzene sulphonyl chloride so as to obtain benzene sulphonyl chloride-indole; (5) performing bromination on the benzene sulphonyl chloride-indole with bromine so as to obtain 5-bromine-benzene sulphonyl chloride-indole; (6) performing protection on the 5-bromine-benzene sulphonyl chloride-indole with a potassium carbonate aqueous solution so as to obtain 5-bromoindole; and (7) performing hydrolysis on the 5-bromoindole with a sodium hydroxide solution under the action of phase transfer catalysis of the kaolin-loaded phosphotungstate so as to obtain a target product. The preparation method disclosed by the invention is high in yield, and can be used for industrial production.
Chemoselective oxidation of aryl organoboron systems enabled by boronic acid-selective phase transfer
Molloy, John J.,Clohessy, Thomas A.,Irving, Craig,Anderson, Niall A.,Lloyd-Jones, Guy C.,Watson, Allan J. B.
, p. 1551 - 1559 (2017/02/10)
We report the direct chemoselective Brown-type oxidation of aryl organoboron systems containing two oxidizable boron groups. Basic biphasic reaction conditions enable selective formation and phase transfer of a boronic acid trihydroxyboronate in the presence of boronic acid pinacol (BPin) esters, while avoiding speciation equilibria. Spectroscopic investigations validate a base-promoted phase-selective discrimination of organoboron species. This phenomenon is general across a broad range of organoboron compounds and can also be used to invert conventional protecting group strategies, enabling chemoselective oxidation of BMIDA species over normally more reactive BPin substrates. We also demonstrate the selective oxidation of diboronic acid systems with chemoselectivity predictable a priori. The utility of this method is exemplified through the development of a chemoselective oxidative nucleophile coupling.
