T:Toxic;
119-65-3Relevant articles and documents
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Barger,Scholz
, (1933)
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The Question of Concerted or Stepwise Mechanisms in Phosphoryl Group (-PO32-) Transfer to Pyridines from Isoquinoline-N-phosphonate
Bourne, Nicholas,Williams, Andrew
, p. 3357 - 3358 (1983)
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Visible-Light-Mediated Photocatalytic Aerobic Dehydrogenation of N-heterocycles by Surface-Grafted TiO2 and 4-amino-TEMPO
Balayeva, Narmina O.,Zheng, Nan,Dillert, Ralf,Bahnemann, Detlef W.
, p. 10694 - 10704 (2019)
Herein, the visible-light-induced dehydrogenation of N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, and indolines in O2-containing suspensions of a commercially available titanium dioxide photocatalyst yielding the corresponding heteroarenes is presented. 4-Amino-2,2,6,6-tetramethylpipiridinyloxyl (4-amino-TEMPO) was found to exhibit a beneficial role, as it increased the yield and improved the selectivity of the dehydrogenation reaction. Both the selectivity and the yield are further enhanced by grafting 0.1 wt % of Ni(II) ions onto the TiO2 surface. It is proposed that the basic reactant adsorbs at Lewis acid sites present at the TiO2 surface. The dehydrogenation reaction is initiated by visible-light excitation of the resulting surface complex and a subsequent single-electron transfer from the excited N-heterocycle via the conduction band of TiO2 to O2. Ni(II) ions possibly serve as an electron transfer bridge between the conduction band of TiO2 and O2, while the TEMPO derivative is assumed to act as a selective redox mediator involved in reactions of the generated reactive oxygen species.
Structural verification of a tetrahydrotetrazole compound
Breton, Gary W.,Hahn, Lauren A.,Martin, Kenneth L.
, p. 1208 - 1212 (2019)
Tetrahydrotetrazoles are five-membered-ring heterocycles containing four contiguous saturated nitrogen atoms. Very few examples of such compounds have been reported in the literature. Our previous attempt at the synthesis of a member of this class of compound suggested that the N - N bonds may be more labile than expected. This finding raised the question as to whether the structures of any of the previously reported tetrahydrotetrazoles had been properly assigned. We have reproduced the synthesis of a reported tetrahydrotetrazole, namely 1,2-di-tert-butyl 3-phenyl-1H,2H,3H,10bH-[1,2,3,4]tetrazolo[5,1-a]isoquinoline-1,2-dicarboxylate, C25H30N4O4, and have now confidently confirmed its structure via X-ray crystallography. However, while sufficiently stable in the crystal phase, we discovered that it remains very labile in solution (having a half-life of only 15min at 20°C in CDCl3). A tentative reaction pathway for its dissociation based on 1H NMR spectral evidence is provided.
Heterogeneous nickel-catalysed reversible, acceptorless dehydrogenation of N-heterocycles for hydrogen storage
Ryabchuk, Pavel,Agapova, Anastasiya,Kreyenschulte, Carsten,Lund, Henrik,Junge, Henrik,Junge, Kathrin,Beller, Matthias
, p. 4969 - 4972 (2019)
Nickel-based nanocatalysts were used in acceptorless, reversible dehydrogenation and hydrogenation reactions of N-heterocycles. Both processes were realized in the same solvent using a single catalyst, without isolation of products and workup, which makes it attractive for hydrogen storage purposes. This concept has been demonstrated in a continuous hydrogenation/dehydrogenation sequence of quinaldine with negligible loss in activity of the nickel catalyst after three hydrogen storage cycles. The scope of acceptorless dehydrogenation has been explored and control experiments suggest that hydrogen liberation is initiated via amine dehydrogenation and supports the direct alkane dehydrogenation from the partially oxidized N-heterocycles.
Hydrogenation/dehydrogenation of N-heterocycles catalyzed by ruthenium complexes based on multimodal proton-responsive CNN(H) pincer ligands
álvarez, Eleuterio,Hernández-Juárez, Martín,López-Serrano, Joaquín,Paneque, Margarita,Rendón, Nuria,Sánchez, Práxedes,Santos, Laura L.,Suárez, Andrés
, p. 9583 - 9587 (2020)
Ru complexes based on lutidine-derived pincer CNN(H) ligands having secondary amine side donors are efficient precatalysts in the hydrogenation and dehydrogenation of N-heterocycles. Reaction of a Ru-CNN(H) complex with an excess of base produces the formation of a Ru(0) derivative, which is observed under catalytic conditions.
New light-induced iminyl radical cyclization reactions of acyloximes to isoquinolines
Alonso, Rafael,Campos, Pedro J.,Garcia, Barbara,Rodriguez, Miguel A.
, p. 3521 - 3523 (2006)
An efficient photochemical approach for the unusual generation of six-membered heterocyclic rings is reported. Iminyl radicals, generated by the irradiation of acyloximes, participate in intramolecular cyclization processes and in intermolecular addition-intramolecular cyclization sequences.
The selective deiodination of iodoheterocycles using the PhSiH3 - In(OAc)3 system
Sugimoto, Osamu,Sugiyama, Minami,Tanji, Ken-ichi
, p. 601 - 606 (2010)
Nitrogen-containing π-deficient heterocyclic iodides such as iodoquinolines or iodopyridines were deiodinated by treatment with phenylsilane catalyzed by indium acetate to give the corresponding deiodinated heterocycles at ambient temperature.
Pyridinium chloride: A new reagent for N-demethylation of N-methylazinium derivatives
Ruiz, Anthony,Rocca, Patrick,Marsais, Francis,Godard, Alain,Queguiner, Guy
, p. 6205 - 6208 (1997)
A new N-demethylation reaction of N-methylazinium derivatives by using boiling pyridinium chloride is described. The reaction is quite clean, fast and yields are almost quantitatives.
MOF-253-Supported Ru Complex for Photocatalytic CO2 Reduction by Coupling with Semidehydrogenation of 1,2,3,4-Tetrahydroisoquinoline (THIQ)
Deng, Xiaoyu,Qin, Yuhuan,Hao, Mingming,Li, Zhaohui
, p. 16574 - 16580 (2019)
MOF-253 (Al(OH)(dcbpy), dcbpy = 2,2′-bipyridine-5,5′-dicarboxylic acid) obtained via a microwave-assisted synthesis was used for the construction of a supported Ru complex containing dcbpy (MOF-253-Ru(dcbpy)2) by coordinating its open N,N′-chelating sites with Ru(II) in Ru(dcbpy)2Cl2. The as-obtained MOF-253-Ru(dcbpy)2 acts as a bifunctional photocatalyst for simultaneous CO2 reduction to produce formic acid and CO, as well as semidehydrogenation of 1,2,3,4-tetrahydroisoquinoline (THIQ) to obtain 3,4-dihydroisoquinoline (DHIQ). The performance over the surface-supported MOF-253-Ru(dcbpy)2 is superior to that over Ru-doped MOF-253 (Ru-MOF-253) obtained via a mix-and-match strategy, indicating that the use of open coordination sites in the MOFs for direct construction of a surface-supported complex is a superior strategy to obtain an MOF-supported homogeneous complex. This study shows the possibility of using an MOF as a platform for the construction of multifunctional heterogeneous photocatalytic systems. The coupling of photocatalytic CO2 reduction with the highly selective dehydrogenation of organics provides an economical and green strategy in photocatalytic CO2 reduction and production of valuable organics simultaneously.
Oxidation of Secondary Amines with NiSO4-K2S2O8
Yamazaki, Shigekazu
, p. 823 - 826 (1992)
The catalytic system consisting of NiSO4 and K2S2O8 has been found to be effective for the oxidation of secondary amines to imines. 1,2,3,4-Tetrahydroisoquinoline was oxidized to 3,4-dihydroisoquinoline as the main product with a small amount of isoquinoline.N-Benzylaniline gave N-benzylideneaniline and a N-N coupling dimer.
Debromination of 8-bromo-2'-deoxyguanosine by methylene blue and visible light
Venkatarangan, Lata,Yang, Dan-Hui,Epling, Gary A.,Basu, Ashis K.
, p. 1441 - 1444 (1999)
Debromination of 8-bromo-2'-deoxyguanosine was accomplished in high yield under neutral conditions in aqueous methanol by irradiating with visible light in the presence of methylene blue as a sensitizer and triethylamine as an electron donor. The method can be extended for the debromination of other bromoaromatic compounds.
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Pictet,Spengler
, p. 2034 (1911)
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Monomeric vanadium oxide: A very efficient species for promoting aerobic oxidative dehydrogenation of N-heterocycles
Xie, Zhenbing,Chen, Bingfeng,Zheng, Lirong,Peng, Fangfang,Liu, Huizhen,Han, Buxing
, p. 431 - 437 (2021)
Monomeric active species are very interesting in heterogeneous catalysis. In this work, we proposed a method to prepare VOx-NbOy@C catalysts, which involve the one-pot hydrothermal synthesis of inorganic/organic hybrid materials containing V/Nb followed by thermal treatment under a reducing atmosphere. The prepared catalysts were characterized using different techniques, such as high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy. It was shown that monomeric VOx species were dispersed homogeneously in the catalysts. The VOx-NbOy@C catalysts displayed high performance in the aerobic oxidative dehydrogenation of N-heterocycles to aromatic heterocycles. It was demonstrated that the selectivity of reaction over the catalyst with a very small amount of V (0.07 wt%) was much higher than that over the NbOy@C, and the catalyst also exhibited excellent stability in the reaction. The detailed study indicated that monomeric VO2 species were the most effective for promoting the reaction. This journal is
Efficient acceptorless dehydrogenation of hydrogen-rich N-heterocycles photocatalyzed by Ni(OH)2@CdSe/CdS quantum dots
Liu, Yanpeng,Yu, Tianjun,Zeng, Yi,Chen, Jinping,Yang, Guoqiang,Li, Yi
, p. 3810 - 3817 (2021)
Hydrogen storage using liquid organic hydrogen carriers (LOHCs) is a promising hydrogen storage technology; however, the hydrogen release process typically requires a high temperature. Developing dehydrogenation technology under mild conditions is highly desirable. Herein, a new approach for photocatalytic acceptorless dehydrogenation of hydrogen-rich LOHCs using Ni(OH)2@CdSe/CdS QDs as the photocatalyst was demonstrated. 1,2,3,4-Tetrahydroquinoline (THQ), iso-THQ, indoline, and their derivatives were selected as hydrogen-rich substrates, which exhibit excellent dehydrogenation efficiency with the release of hydrogen photocatalyzed by Ni(OH)2@CdSe/CdS QDs. Up to 100% yields of hydrogen and over 90% yields of complete dehydrogenation products were obtained at ambient temperature. Isotope tracer studies indicate a stepwise pathway, beginning with the photocatalytic oxidation of the substrate to release a proton and followed by proton exchange with heavy water. This work provides a promising alternative strategy to develop highly efficient, low cost and earth-abundant photocatalysts for acceptorless dehydrogenation of hydrogen-rich LOHCs.
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Burstin
, p. 1443 (1913)
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Rh/TiO2-Photocatalyzed Acceptorless Dehydrogenation of N-Heterocycles upon Visible-Light Illumination
Bahnemann, Detlef W.,Balayeva, Narmina O.,Dillert, Ralf,Mamiyev, Zamin,Zheng, Nan
, p. 5542 - 5553 (2020)
TiO2 is an effective and extensively employed photocatalyst, but its practical use in visible-light-mediated organic synthesis is mainly hindered by its wide band gap energy. Herein, we have discovered that Rh-photodeposited TiO2 nanoparticles selectively dehydrogenate N-heterocyclic amines with the concomitant generation of molecular hydrogen gas in an inert atmosphere under visible light (λmax = 453 nm) illumination at room temperature. Initially, a visible-light-sensitive surface complex is formed between the N-heterocycle and TiO2. The acceptorless dehydrogenation of N-heterocycles is initiated by direct electron transfer from the HOMO energy level of the amine via the conduction band of TiO2 to the Rh nanoparticle. The reaction condition was optimized by examining different photodeposited noble metals on the surface of TiO2 and solvents, finding that Rh0 is the most efficient cocatalyst, and 2-propanol is the optimal solvent. Structurally diverse N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, indolines, and others bearing electron-deficient as well as electron-rich substituents underwent the dehydrogenation in good to excellent yields. The amount of released hydrogen gas evinces that only the N-heterocyclic amines are oxidized rather than the dispersant. This developed method demonstrates how UV-active TiO2 can be employed in visible-light-induced synthetic dehydrogenation of amines and simultaneous hydrogen storage applications.
Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
Fiorio, Jhonatan L.,Rossi, Liane M.
, p. 312 - 318 (2021/01/29)
The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
supporting information, p. 7738 - 7744 (2021/05/07)
Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
