- An isocyanide based multi-component reaction under catalyst- and solvent-free conditions for the synthesis of unsymmetrical thioureas
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A new and efficient method for the synthesis of thiourea derivatives by a sequential one-pot, three-component reaction between aromatic isocyanides, amines, and 1,2-di-tert-butyldisulfane (DTBS) was developed and 27 different examples were synthesized in good to excellent yields. DTBS was identified as an effective sulfur surrogate without the use of both catalysts and solvents. This protocol does not employ any transition metal catalyst or special experimental setup.
- Singh, Karandeep,Sharma, Siddharth
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p. 197 - 201
(2016/12/28)
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- Eosin y catalyzed visible-light-promoted aerobic oxidative cyclization of 2-aminobenzothiazole
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A mild and efficient one-pot visible light irradiated synthesis of 2-aminobenzothiazole 4(a-l) from arylisothiocyanate 1(a-l) and secondary amines 2 have been reported in presence of eosin Y as an organophotoredox catalyst at room temperature under aerobi
- Srivastava, Vishal,Singh, Pravin K.,Singh, Praveen P.
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p. 227 - 233
(2016/01/20)
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- Cerium ammonium nitrate-catalyzed aerobic oxidative coupling of dithiocarbamates: Facile synthesis of thioureas and bis(aminothiocarbonyl)disulfides
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Diverse disubstituted and trisubstituted thioureas were synthesized by the condensation of dithiocarbamate TEA (or DABCO) salts and amines using cerium ammonium nitrate (CAN) as a catalyst in high yields at room temperature. It is a one-pot method and it is unnecessary to isolate isothiocyanates. This reaction probably took place through nucleophilic addition of amines to isothiocyanates, which were generated by oxidative coupling of dithiocarbamates and the following decomposition of bis(aminothiocarbonyl)disulfides. When secondary amines and CS2served as the reactants, bis(aminothiocarbonyl)disulfides were obtained via tandem nucleophilic addition/oxidative coupling reactions in moderate to excellent yields. In all the coupling reactions, the oxidant was air and CAN possibly acted as an SET catalyst.
- Li, Tian-Tian,Song, Xiang-Hai,Wang, Mei-Shuang,Ma, Ning
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p. 40054 - 40060
(2014/12/10)
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- A non-isothiocyanate route to synthesize trisubstituted thioureas of arylamines using in situ generated dithiocarbamates
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A novel, user-friendly, and convenient method for the synthesis of trisubstituted thioureas of arylamines is presented, for the first time, using in situ generated dithiocarbamates of secondary amines. This strategy provides an excellent opportunity to access thioureas containing primary aryl amines. A non-isothiocyanate route to obtain thioureas is the advantage of this strategy, which may provide a useful route to synthesize a variety of biologically active derivatives of thioureas.
- Varun, Begur Vasanthkumar,Prabhu, Kandikere Ramaiah
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p. 3079 - 3087
(2013/04/24)
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- A ligand free copper(II) catalyst is as effective as a ligand assisted Pd(II) catalyst towards intramolecular C-S bond formation via C-H functionalization
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Copper(I) catalysts are usually ineffective on the other hand Pd(II) catalysts are quite effective in promoting intramolecular sp2 C-H functionalization (C-S bond formation). Herein, we have developed a ligand assisted Pd(II) catalyzed C-S bond formation via C-H activation from arylthioureas leading to the formation of 2-aminobenzothiazoles for substrates bearing electron donating (EDG) groups in the aryl ring. However without the assistance of ligand this Pd(II) catalyzed reaction is quite unproductive particularly for thioureas possessing strongly electron donating groups in the aryl rings. Interestingly, the ligand free Cu(II) catalyzed oxidative cyclization of arylthioureas are equally effective both for arylthioureas possessing electron donating as well as electron withdrawing groups in the aryl rings.
- Banerjee, Arghya,Santra, Sourav Kumar,Rout, Saroj Kumar,Patel, Bhisma K.
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p. 9096 - 9104
(2013/09/24)
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- A model for a solvent-free synthetic organic research laboratory: Click-mechanosynthesis and structural characterization of thioureas without bulk solvents
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The mechanochemical click coupling of isothiocyanates and amines has been used as a model reaction to demonstrate that the concept of a solvent-free research laboratory, which eliminates the use of bulk solvents for either chemical synthesis or structural characterization, is applicable to the synthesis of small organic molecules. Whereas the click coupling is achieved in high yields by simple manual grinding of reactants, the use of an electrical, digitally controllable laboratory mill provides a rapid, quantitative and general route to symmetrical and non-symmetrical aromatic or aromatic-aliphatic thioureas. The enhanced efficiency of electrical ball milling techniques, neat grinding or liquid-assisted grinding, over manual mortar-and-pestle synthesis is demonstrated in the synthesis of 49 different thiourea derivatives. Comparison of powder X-ray diffraction data of mechanochemical products with structural information found in the Cambridge Structural Database (CSD), or obtained herein through single crystal X-ray diffraction, indicates that the mechanochemically obtained thiourea derivatives are pure in a chemical sense, but can also demonstrate purity in a supramolecular sense, i.e. in all structurally explored cases the product consisted of a single polymorph. As an extension of our previous work on solvent-free synthesis of coordination polymers, it is now demonstrated that such polymorphic and chemical purity of selected thiourea derivatives, the latter being evidenced through quantitative reaction yields, can enable the direct solvent-free structural characterization of mechanochemical products through powder X-ray diffraction aided by solid-state NMR spectroscopy.
- Strukil, Vjekoslav,Igrc, Marina D.,Fabian, Laszlo,Eckert-Maksic, Mirjana,Childs, Scott L.,Reid, David G.,Duer, Melinda J.,Halasz, Ivan,Mottillo, Cristina,Friscic, Tomislav
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supporting information
p. 2462 - 2473
(2013/02/21)
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- Highly efficient and catalyst-free synthesis of unsymmetrical thioureas under solvent-free conditions
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A highly efficient and simple synthesis of unsymmetrical thioureas is reported based on the reaction of readily synthesized dithiocarbamates with amines, without using any catalyst under solvent-free conditions. The short reaction time, high yields, and s
- Halimehjani, Azim Ziyaei,Pourshojaei, Yaghoub,Saidi, Mohammad R.
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scheme or table
p. 32 - 34
(2009/04/10)
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