- Synthesis, electrochemical investigation and EPR spectroscopy of a reversible four-stage redox system based on mesoionic 5,5'-azinobis(1,3-diphenyltetrazole) and related mesoionic compounds
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Mesoionic 5,5'-azinobis(1,3-diphenyltetrazole) 1 was prepared, and its chemical oxidation gave stable crystals of the corresponding radical cation 1.+ and dication 12+, which reversibly gave back azine 1 on reduction with zinc. Electrochemical investigations of 1 using cyclovoltammetry and differential pulse voltammetry in pyridine (Py) or dichloromethane (DCM) also revealed the two reversible successive one-electron oxidations leading to dication 12+ via radical cation 1.+, both of which can be reduced to the neutral state 1. In the cathodic process, 1 was reduced by two consecutive one-electron transfers at only slightly different potentials up to the corresponding diamon 12- which could be re-oxidized to the neutral state; thus constituting a reversible four-stage redox system. Radical cation 1.+ and anion 1.- were characterized by EPR spectroscopy. In order to get more insights into the spin-density distribution of 1.+, the bis- and tetra-15N-labelled species 1a.+, 1b.+ and 1c.+ were synthesized and investigated by EPR and 15N as well as 14N ENDOR spectroscopy, revealing that the largest N hyperfine coupling constants are due to the nitrogen atoms of the central bridge. According to 1H ENDOR there seems to be a small coupling with the protons of both phenyl rings which cannot be resolved in the EPR spectrum. The electrochemical properties of the related mesoionic compounds 5-10 were also investigated in Py or DCM solutions. In the cathodic process, a reduction peak of 9 and 10 was observed due to their reversible one-electron reduction to the corresponding radical anions. The radical obtained on reduction of 10 was characterized by EPR spectroscopy. On the other hand, 5-8 can be reduced by a formal two-electron transfer up to the corresponding dianions which are re-oxidizable to the neutral state. In the anodic process, 9/10 undergo irreversible one-electron oxidations whereas 5/6 (in DCM) and 7/8 (in Py) experience reversible or irreversible step by step two-electron oxidations leading to the dications. In Py the oxidation products of 5/6 react to further species revealing two more oxidation and several rereduction peaks. On the other hand, the oxidation products of 7/8 are instable in DCM (one main oxidation and rereduction peak). The electrochemical data are discussed in terms of delocalization in the cations and conjugation in the dications.
- Araki, Shuki,Yamamoto, Kaori,Inoue, Tomoko,Fujimoto, Koji,Yamamura, Hatsuo,Kawai, Masao,Butsugan, Yasuo,Zhou, Jinkui,Eichhorn, Emerich,Rieker, Anton,Huber, Martina
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- A traceless linker approach to the solid phase synthesis of substituted guanidines utilizing a novel acyl isothiocyanate resin
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Solid phase synthesis of a series of substituted guanidines based on a novel acyl isothiocyanate resin is presented. This method provides both mono and disubstituted guanidines with a variety of sterically demanding and/or electron withdrawing substituents in good purities and yields.
- Wilson, Lawrence J.,Klopfenstein, Sean R.,Li, Min
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- An expedient synthesis of substituted guanidines
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This work discusses a rapid synthesis of substituted guanidines from 1,3-disubstituted thioureas copper sulphate-silica gel in the presence of an amine. The method surpasses the previous known methods for the synthesis.
- Ramadas, Krishnamurthy
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Read Online
- Lac sulfur on alumina-triethanolamine - An effective reagent for the synthesis of substituted guanidines
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A direct synthesis of substituted guanidines is reported from their thiourea analogues. The strategy adopted is a concise approach to the synthesis of the title compounds.
- Ramadas, Krishnamurthy
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Read Online
- Continuous production method for vulcanization accelerator DPG
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The invention provides a continuous production method for a vulcanization accelerator DPG. The method comprises the following steps that (1) diphenylthiourea, a catalyst, ammonium hydroxide and an organic solvent are mixed to obtain a reaction raw material mixture; (2) the reaction raw material mixture and an oxidizing agent are subjected to an oxidation reaction in a continuous flow reactor to obtain a reaction product; (3) the reaction product is post-treated to obtain the vulcanization accelerator DPG, wherein the organic solvent in step (1) can dissolve the diphenylthiourea and the vulcanization accelerator DPG. The method reduces the pressure in the reaction process, improves the utilization rate of the raw materials, stabilizes the product quality, greatly shortens the reaction timecompared with a conventional technology, improves the reaction yield, and effectively overcomes the disadvantage of traditional kettle type batch production.
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Paragraph 0046-0050; 0054; 0055; 0061; 0066; 0067; 0072-0073
(2018/10/19)
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- Synthesis of symmetrical and unsymmetrical N, N ′-diaryl guanidines via copper/N-methylglycine-catalyzed arylation of guanidine nitrate
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CuI/N-methylglycine-catalyzed coupling reaction of guanidine nitrate with both aryl iodides and bromides takes place at 70-100 °C, affording symmetrical N,N′-diaryl guanidines with good to excellent yields. Unsymmetrical N,N′-diaryl guanidines can be assembled via monoarylation of guanidine nitrate with aryl iodides bearing a strong electron-withdrawing group and subsequent coupling with another aryl iodide.
- Xing, Hui,Zhang, Ye,Lai, Yisheng,Jiang, Yongwen,Ma, Dawei
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experimental part
p. 5449 - 5453
(2012/08/07)
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- Direct guanidinylation of aryl and heteroaryl halides via copper-catalyzed cross-coupling reaction
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A modified Ullmann reaction using p-methoxybenzyl (PMB) guanidine as guanidinylation agent yielded various aryl and heteroaryl guanidines in good yields.
- Hammoud, Hassan,Schmitt, Martine,Bihel, Frederic,Antheaume, Cyril,Bourguignon, Jean-Jacques
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p. 417 - 423
(2012/03/09)
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- O-Iodoxybenzoic acid mediated oxidative condensation: Synthesis of guanidines using 1,-3-disubstituted thiourea precursors
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An efficient and mild oxidative condensation procedure using o-iodoxybenzoic acid and triethylamine or ammonia as base has been developed for the synthesis of guanidines starting from easily synthesizable 1,3-disubstituted thioureas and amines or ammonia.
- Dangate, Prasad S.,Akamanchi, Krishnacharya G.
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p. 6765 - 6767
(2013/01/15)
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- Copper-catalyzed guanidinylation of aryl iodides: The formation of N,N′-disubstituted guanidines
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Chemical Equation Presented A copper-catalyzed cross-coupling reaction of guanidine nitrate with aryl iodides was used for the formation of N,N′-disubstituted guanidines to be used as potential therapeutics for strokes. A relatively inexpensive commercially available guanidine salt and a series of aryl iodides together with copper iodide and N,N-diethylsalicylamide as an efficient catalyst/1 igand system provided a simple diarylation procedure.
- Cortes-Salva, Michelle,Nguyen, Be-Lan,Cuevas, Javier,Pennypacker, Keith R.,Antilla, Jon C.
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supporting information; experimental part
p. 1316 - 1319
(2010/06/15)
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- HETEROARYL GUANIDINES ; INHIBITORS OF VIRAL REPLICATION
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Compounds of Formula (1), and pharmaceutically acceptable forms thereof, are provided wherein the variables X, Y, Z, Al, R2, R3, R4, R5 and R6 are defined herein. Certain compounds of Formula 1 described herein which possess potent antiviral activity. Certain compounds of Formula (1) that are potent and/ or selective inhibitors of Hepatitis C virus replication. Pharmaceutical compositions containing one or more compounds of Formula (1), or a salt, solvate, or acylated prodrug of such compounds, and one or more pharmaceutically acceptable carriers, excipients, or diluents are also provided. Methods of treating patients suffering from certain infectious diseases by administering to such patients an amount of a compound of Formula (1) effective to reduce signs or symptoms of the disease or disorder are disclosed. These infectious diseases include viral infections, particularly HCV infections. Methods of treating human patients suffering from an infectious disease, but also encompasses methods of treating other animals, including livestock and domesticated companion animals, suffering from an infectious disease. Methods of treatment include administering a compound of Formula (1) as a single active agent or administering a compound of Formula (1) in combination with on or more other therapeutic agent.
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Page/Page column 42-43
(2008/06/13)
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- Direct synthesis of guanidines using di(imidazole-1-yl)methanimine
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A direct synthetic approach to guanidine compounds is reported here using di(imidazole-1-yl)methanimine and di(imidazole-1-yl)cyanomethanimine as guanylating reagents.
- Wu, Yong-Qian,Hamilton, Sean K.,Wilkinson, Douglas E.,Hamilton, Gregory S.
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p. 7553 - 7556
(2007/10/03)
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- Role of quaternaryammonium permanganates in the synthesis of substituted guanidines - A comparative study
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Quaternaryammonium permanganate transforms 1,3-diarylthioureas in the presence of an amine to the respective trisubstituted guanidines in excellent yields.
- Srinivasan, Natarajan,Ramadas, Krishnamurthy
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p. 343 - 346
(2007/10/03)
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- Novel linker for the solid-phase synthesis of guanidines
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A novel linker for the generation of alkyl-, acyl- and arylguanidines as an attachment point in solid phase synthesis has been developed. Introduction of a suitably functionalized thiourea to Wang resin via a carbamate linkage, followed by displacement of sulfur with a 1°or 2°amine affords resin bound guanidines suitably protected for further manipulation. Activation of the thiourea with Mukaiyama's reagent allows for the generation of arylguanidines. Mild acid treatment effects deprotection and liberation from the resin to afford guanidines in good yield and high purity.
- Josey, John A.,Tarlton, Catherine A.,Payne, Courtney E.
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p. 5899 - 5902
(2007/10/03)
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- A Short and Concise Synthesis of Guanidines
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A facile high yielding process of guanidines is reported by reaction of amine nucleophiles on the oxidised thioureas in an aqueous medium using the unexploited reagents sodium chlorite and sodium metaperiodate for the oxidation of 1,3-disubstituted thioureas.
- Ramadas,Janarthanan,Pritha
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p. 1053 - 1054
(2007/10/03)
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- REACTION OF DIPHENYLGUANIDINE WITH DIORGANYLDITHIOPHOSPHORIC ACIDS
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Following the investigation of the reaction of N,N'-diphenylguanidine with diorganyldithiophosphoric acids, it was shown that the reaction leads to the formation of diorganyldithiophosphate salts of N,N'-diphenylguanidine with a protonated nitrogen atom.The dithiophosphate salts of N,N'-diphenylguanidine decompose on heating to the starting compounds.The action of heat causes the disproportionation of the dithiophosphoric acids into O,O,S-triorganyl dithiophosphate and O-monoorganyl dithiophosphate.
- Fridland, S. V.,Shaikhiev, I. G.,Mukhutdinov, A. A.,Il'yasov, A. V.,Musin, R. Z.
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p. 575 - 578
(2007/10/02)
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- Bicyclic amidines
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New amidine/isocyanate adducts are particularly useful as catalysts for hardening epoxy resins, in particular pulverulent coating compositions based on epoxy resins. New bicyclic amidines are excellent starting materials for manufacturing these amidine/isocyanate adducts.
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