- Nitroarenes as versatile building blocks for the synthesis of unsymmetrical urea derivatives and N-Arylmethyl-2-substituted benzimidazoles
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In this contribution, a fast and simple method for the synthesis of unsymmetrical urea derivatives and N-arylmethyl-2-substituted benzimidazoles was developed starting from nitroarenes. The reaction of nitroarenes and phenyl isocyanate or phenyl isothiocyanate in tin (II) chloride dihydrate/choline chloride eutectic mixture afforded the expected urea and thiourea derivatives, while the reaction of different aldehydes with o-nitroaniline or 4-methoxy-2-nitroaniline shows a markedly high preference for the obtention of N-arylmethyl-2-substituted benzimidazoles over the 2-substituted analogues. This method offers a straightforward alternative to obtain the target compounds in good to excellent yields with short reaction times employing an operationally simple experimental set-up. Graphic abstract: [Figure not available: see fulltext.] A series of unsymmetrical urea and thiourea derivatives together with 1,2-disubstituted benzimidazoles are easily obtained in good yields starting from nitroarenes employing the eutectic mixture tin (II) chloride dihydrate/choline chloride as reductive reaction media.
- Rodríguez-Huerto, Paula A.,Pe?a-Solórzano, Diana,Ochoa-Puentes, Cristian
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p. 6275 - 6283
(2021/07/29)
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- Hydroamination and Hydrophosphination of Isocyanates/Isothiocyanates under Catalyst-Free Conditions
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Symmetrical and unsymmetrical N,N’-disubstituted as well as trisubstituted ureas/thioureas by the hydroamination of isocyanates/isothiocyanates, and various phosphathioureas by the hydrophosphination of isothiocyanates have been synthesized in good to excellent yields under catalyst-free and mild conditions. This protocol is also applicable for the efficient synthesis of chiral ureas and thioureas and common herbicides, such as fenuron and monuron.
- Zhu, Xiancui,Xu, Mengchen,Sun, Jinrong,Guo, Dianjun,Zhang, Yiwei,Zhou, Shuangliu,Wang, Shaowu
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p. 5213 - 5218
(2021/10/19)
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- Tunable NIR-II emitting silver chalcogenide quantum dots using thio/selenourea precursors: Preparation of an MRI/NIR-II multimodal imaging agent
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Aqueous-stable, Cd- and Pb-free colloidal quantum dots with fluorescence properties in the second near-infrared region (NIR-II, 1000-1400) are highly desirable for non-invasive deep-tissue optical imaging and biosensing. The low band-gap semiconductor, silver chalcogenide, offers a non-toxic and stable alternative to existing Pd, As, Hg and Cd-based NIR-II colloidal quantum dots (QDs). We report facile access to NIR-II emission windows with Ag2X (X = S, Se) QDs using easy-to-prepare thio/selenourea precursors and their analogues. The aqueous phase transfer of these QDs with a high conservation of fluorescence quantum yield (retention up to ~90%) and colloidal stability is demonstrated. A bimodal NIR-II/MRI contrast agent with a tunable fluorescence and high T1 relaxivity of 408 mM-1 s-1 per QD (size ~ 2.2 nm) and 990 mM-1 s-1 per QD (size ~ 4.2 nm) has been prepared by grafting 50 and 120 monoaqua Gd(iii) complexes respectively to two differently sized Ag2S QDs. The size of the nanocrystals is crucial for tuning the Gd payload and the relaxivity.
- Basel, Siddhant,Bhardwaj, Karishma,Borthakur, Sukanya,Brito, Beatriz,Clarke, Mitchell,Pariyar, Anand,Pradhan, Sajan,Roy, Pankaj,Saikia, Lakshi,Shankar, Amit,Stasiuk, Graeme J.,Tamang, Sudarsan,Thapa, Surakcha
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supporting information
p. 15425 - 15432
(2020/11/18)
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- Synthesis and Reactivity of NNNNN-Pincer Multidentate Pyrrolyl Rare-Earth-Metal Amido-Chloride or Dialkyl Complexes
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The NNNNN-pincer multidentate pyrrolyl rare-earth-metal amido-chloride complexes {η1:κ3-2,5-[CH3N(CH2CH2)2NCH2]2C4H2N}RECl[N(SiMe3)2] (RE = Y (2a), Sm (2b), Dy (2c), Er (2d), Yb (2e)) were synthesized by one step from reactions of [(Me3Si)2N]3RE(μ-Cl)Li(T
- Cui, Peng,Du, Jun,Huang, Zeming,Sheng, Weiming,Wang, Shaowu,Wei, Yun,Xu, Xiaolong,Zhang, Lijun,Zhang, Xiuli,Zhou, Shuangliu,Zhu, Xiancui
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supporting information
p. 4525 - 4534
(2020/12/22)
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- One-pot synthesis of highly functionalized benzo [1,3] thiazine from isocyanides, aniline, and heterocumulene via Cu-catalyzed intramolecular C-H activation reactions
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A one-pot synthesis of functionalized benzo thiazine derivatives via a Cu-catalyzed, multicomponent reaction of isocyanides, aniline, and heterocumulenes in acetonitrile at room temperature was developed. Transition metal-catalyzed activation of C-H bonds
- Dastjerdi, Hossein F.,Nematpour, Manijeh,Rezaee, Elham,Jahani, Mehdi,Tabatabai, Sayyed A.
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p. 1537 - 1541
(2019/07/12)
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- A facile method for the preparation of carbodiimides from thioureas and (Boc)2O
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A concise method for the preparation of carbodiimides from thioureas using di-tert-butyl dicarbonate [(Boc)2O] as the dehydrosulfurizative reagent has been developed. Using DMAP as the catalyst, a variety of symmetric and asymmetric 1,3-diaryl thioureas were converted into the corresponding carbodiimides efficiently in a short time.
- Wu, He,Sun, Yan-Fang,Zhang, Chen,Miao, Chun-Bao,Yang, Hai-Tao
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supporting information
p. 739 - 742
(2018/01/27)
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- Palladium catalyzed carbonylative annulation of the C(sp2)-H bond of N,1-diaryl-1H-tetrazol-5-amines and N,4-diaryl-4H-triazol-3-amines to quinazolinones
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Pd(ii) catalyzed direct C-H carbonylative annulation of N,1-diaryl-1H-tetrazol-5-amines and N,4-diaryl-4H-1,2,4-triazol-3-amines gave the corresponding triazole and tetrazole fused quinazolinones in good yields. This methodology offers a convenient method for the synthesis of these important heterocyclic scaffolds in a highly atom economical process. On the mechanistic aspect weakly nucleophilic triazole and tetrazole moieties function as both directing as well as intramolecular nucleophiles. The catalytically active C-H activated intermediate dimeric Pd complex was isolated and characterized which on exposure to CO gas gave the corresponding tetrazole fused quinazolinone derivative. On the basis of isolation of the intermediate and observed kinetic isotope effects, a mechanism has been proposed for the C-H activated direct carbonylative annulation reaction.
- Chandrasekhar, Attoor,Ramkumar, Venkatachalam,Sankararaman, Sethuraman
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supporting information
p. 8629 - 8638
(2018/12/12)
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- Nickle Catalysis Enables Access to Thiazolidines from Thioureas via Oxidative Double Isocyanide Insertion Reactions
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An efficient synthesis of thiazolidine-2,4,5-triimine derivatives was developed via Ni-catalyzed oxidative double isocyanide insertion to thioureas under air conditions, in which thioureas play three roles as a substrate, a ligand, and overcoming isocyanide polymerization. The reaction is featured by employing a low-cost and low loading Ni(acac)2 catalyst, without any additives, and high atom economy. This is the first example to directly apply a Ni(II) catalyst in oxidative double isocyanide insertion reactions.
- Yuan, Wen-Kui,Liu, Yan Fang,Lan, Zhenggang,Wen, Li-Rong,Li, Ming
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supporting information
p. 7158 - 7162
(2018/11/25)
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- 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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- Dual roles of substituted thiourea as reductant and ligand in CuAAC reaction
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A highly efficient catalytic system, CuSO4·5H2O/1-(4-methoxyphenyl)-3-phenylthiourea, for the copper(I)-catalyzed azide–alkyne cycloaddition reaction (CuAAC) was discovered. In the above catalytic system, substituted thiourea acts both as a reductant and a ligand. CuSO4·5H2O/1-(4-methoxyphenyl)-3-phenylthiourea is both an economical and efficient catalyst for the CuAAC reaction. In addition, the new catalytic system has advantageous features including mild and green reaction conditions, and broad substrate compatibility. A variety of 1,4-disubstituted 1,2,3-triazoles have been prepared with good to excellent yields with the CuSO4·5H2O/1-(4-methoxyphenyl)-3-phenylthiourea catalytic system in aqueous solution.
- Wang, Siyu,Jia, Kai,Cheng, Jiajia,Chen, Yu,Yuan, Yaofeng
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supporting information
p. 3717 - 3721
(2017/09/01)
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- Convenient synthesis of unsymmetrical N,N′-disubstituted thioureas in water
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A simple and convenient two-step method has been developed and used to synthesise 25 (4 of which are novel) unsymmetrical N,N′-disubstituted thioureas in water. Alkylamines or variously substituted arylamines reacted smoothly with phenyl chlorothionoformate at room temperature to form thiocarbamates, which were then reacted with another alkyl- or arylamine in water at reflux to afford the unsymmetrical N,N′-disubstituted thioureas in good to excellent yields. Mild conditions, simple work-up, high yields as well as using water as solvent are the major advantages of the method.
- Li, Zhengyi,Chen, Yuan,Yin, Yue,Wang, Zhiming,Sun, Xiaoqiang
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p. 670 - 673
(2016/11/18)
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- Synthesis of some 3,5-disubstituted phenyl-5,6-dihydrofuro[2,3-d]thiazol-2(3H)-ylidene) imines as potential pesticides
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A new series of novel 3,5-disubstituted phenyl-5,6-dihydrofuro[2,3-d]thiazol-2(3H)-ylidene) imines have been synthesized from a common intermediate, in good yield. These compounds have been screened for their herbicidal activities against èchinochloa oryzicola, Echinochloa crus-galli, Oryza sativa, Glycine max and antifungal activities against Aspergillus Niger and Pyricularia oryzae whereas for antimicrobial activities, they have been screened against Salmonella typhi, Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis and Bacillus pumilus.
- Tiwari, Shailendra,Singh, Kamal Pratap,Ahmad, Akeel
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p. 1007 - 1012
(2017/11/10)
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- A simple and straightforward synthesis of phenyl isothiocyanates, symmetrical and unsymmetrical thioureas under ball milling
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Promoted by KOH under ball milling, anilines were efficiently transformed into isothiocyanates (in presence of 5.0 equiv. CS2) or symmetrical thioureas (in presence of 1.0 equiv. CS2), without using any other harsh or toxic decomposition reagent. Some in situ generated isothiocyanates can directly "click" with other amines to afford unsymmetrical thioureas.
- Zhang, Ze,Wu, Hao-Hao,Tan, Ya-Jun
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p. 16940 - 16944
(2013/09/24)
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- Synthesis and characterisation of [(en)2Co]3+ complexes coordinated by substituted thiourea ligands
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Substituted thiourea ligands bind in a bidentate manner forming a four-membered ring through the sulfur atom and a deprotonated thiourea nitrogen atom when reacted with [(en)2Co(OSO2CF3)2]+ in tetramethylene sulfone. Reaction of unsymmetrical ligands results in the formation of coordination isomers, some of which can be separated by column chromatography using Sephadex SPC-25. Coordination isomers are easily distinguishable based on visible and 1H NMR spectroscopy . Twelve para-substituted and one meta-substituted ligands were studied: N,N′-dibenzylthiourea (1a); N-(R)phenyl-N′-benzylthiourea R≤H (2a), NO2 (2b), CH3 (2c); N-(R)phenyl-N′-(R′)phenylthiourea R, R′: H, H (3a), H, CH3 (3b), OCH3, NO2 (3c), CH3, NO2 (3d); N-methyl-N′-(R)phenylthiourea R≤H (4a), CH3 (4b), OCH3 (4c), NO2 (4d), 3-CH3 (4e). The solid state structure (X-ray) of one isomer of Co-4a as its perchlorate salt confirms the coordination mode suggested by 1H NMR spectroscopy and shows that the Co-N bond trans to the coordinated thiourea sulfur induces a structural trans effect of 0.019A.
- Roecker, Lee,Aiyegbo, Mohammed,Al-Haddad, Aladdin,Fletcher, Emily,Kc, Ravi,Hurst, Jason,Lane, Timothy,Larsen, Ryan,Noinaj, Nicholas,Teh, Say Lee,Wade, Samuel K.,Parkin, Sean
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p. 944 - 951
(2013/09/12)
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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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- Tandem regioselective synthesis of tetrazoles and related heterocycles using iodine
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A one-pot, tandem process has been developed for the synthesis of a library of tetrazoles from aryl isothiocyanates. Condensation of aryl isothiocyanates with ammonia, and aryl amines (R-NH2) provided mono, 1,3-disubstituted symmetrical and unsymmetrical thioureas, which on desulfurization with molecular iodine (I2) led to formation of the corresponding heterocumulene (cyanamides or carbodiimides). The in situ generated heterocumulene on subsequent treatment with sodium azide at room temperature gave corresponding tetrazoles. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas was found to be correlated with the basicities (pKa's) of the parent amines attached to the thiourea. Aryl-sec-alkyl unsymmetrical thioureas gave thioamido guanidino products rather than the 5-aminotetrazoles produced by HgCl2 mediation of the reaction. Bis-thioureas derived from aryl isothiocyanates and hydrazine gave thiadiazoles exclusively.
- Yella, Ramesh,Khatun, Nilufa,Rout, Saroj Kumar,Patel, Bhisma K.
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supporting information; experimental part
p. 3235 - 3245
(2011/06/20)
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- Structural requirement of phenylthiourea analogs for their inhibitory activity of melanogenesis and tyrosinase
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Effect of a series of 1-phenylthioureas 1a-k and 1,3-disubstituted thioureas 2a-k were evaluated against melanin formation in melanoma B16 cell line and mushroom tyrosinase. Inhibitory activity of tyrosinase of 1-phenylthioureas 1a-k is parallel to their melanogenic inhibition. Thus, the melanogenic inhibition in melanoma B16 cells of 1-phenylthioureas could be the result of inhibition of tyrosinase. However, 1,3-diaryl or 1-phenyl-3- alkylthioureas, 2a-k, appears as melanogenic inhibitor without inhibition of tyrosinase. The molecular docking study of 1e and 2b to binding pocket of tyrosinase provided convincing explanation regarding the necessity of direct connection of planar phenyl to thiourea unit without N′-substitution of phenylthioureas 1 as tyrosinase inhibitor and 2 as non-tyrosinase inhibitor.
- Thanigaimalai, Pillaiyar,Lee, Ki-Cheul,Sharma, Vinay K.,Joo, Cheonik,Cho, Won-Jea,Roh, Eunmiri,Kim, Youngsoo,Jung, Sang-Hun
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experimental part
p. 6824 - 6828
(2011/12/22)
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- Microwave induced improved synthesis of monoaryl thiocarbamides, 1,3-diarylthiocarbamides, 1,3-diarylcarbamides and monoaryl-2,4-dithiobiurets
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The 1-arylthiocarbamides (3), 1, 3-diarylthiocarbamides (6), 1,3-diarylcarbamides (7) and 1-aryl-2,4-dithiobiurets (11) have been synthesized by the microwave induced heating of respective reactants for about 30-60 s in solvent free condition. Reaction yields are higher with reduced time, period and without the use of any solvent.
- Uberhande,Thakare,Berad
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experimental part
p. 1137 - 1141
(2011/05/05)
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- Synthesis, phytotoxic, cytotoxic, acetylcholinesterase and butrylcholinesterase activities of N,N-diaryl unsymmetrically substituted thioureas
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Fourteen N,N-diaryl unsymmetrically substituted thioureas were synthesised and their cytotoxic (in vitro), phytotoxic (in vitro), acetylcholinesterase and butrylcholinesterase activities were determined. Thiourea 16 exhibited high, and 1 and 3 showed significant phytotoxic activity. Thioureas 1, 3, 4, 6 and 10 showed significant activity and 2, 6 and 7 indicated moderate cytotoxic activities. Compound 12 exhibited butrylcholinesterase activity higher than a standard reference.
- Begum, Saeedan,Choudhary, M. Iqbal,Khan, Khalid M.
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experimental part
p. 1719 - 1730
(2010/05/18)
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- Ultrasound-promoted scavenging: A rapid parallel purification for solution phase combinatorial synthesis
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Ultrasound irradiation enhances the mass transfer and reaction rate in scavenging, avoiding the trouble of time-consuming purification procedure in solution-phase parallel synthesis. An application of this technique is demonstrated in the scavenging of excess isothiocyanates from reaction mixtures.
- Peng, Yanqing,Song, Gonghua,Xu, Xiaoyong
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p. 261 - 263
(2007/10/03)
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- Kinetics of condensation of aryl isothiocyanates with aryl amines
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The kinetics of condensation of aryl isothiocyanates with aryl amines in non-aqueous medium have been investigated. The condensation reaction is first order each in [amines] and [isothiocynates]. The effect of substituents on the rate of condensation and the thermodynamic parameters are evaluated. The reaction products have been isolated and characterized as asymmetric thiocarbamides and a probable mechanism of the condensation proposed.
- Pathrikar, Late G. Y.,Bondge,Burungale,Bhingolikar,Ingle,Mane
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p. 2518 - 2521
(2007/10/03)
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- Unsymmetrically N,N′-Disubstituted Diarylthioureas and Their Coordination Compounds with Cu(II) and Ni(II)
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Some new unsymmetrically N,N′-disubstituted diarylthioureas were prepared, and their reactions of complex formation in solutions were studied. Coordination compounds of the synthesized thioureas with 3d metals(2+) (Cu, Ni) were isolated and shown to have a chelate structure of the general formula M(SN)2.
- Cheresova,Zhukova,Tatarintseva,Cheresov,Mukmeneva
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p. 1271 - 1275
(2007/10/03)
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- Desulfurization of N,N'-Diarylthioureas by Lead Tetraacetate Oxidation
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Lead tetraacetae oxidation of N,N'-diarylthioureas in refluxing dichloromethane and pyridine gave the corresponding N,N'-diarylureas.Sulfur was isolated during each oxidation reaction.
- Debroy, Abhijit,Nandy Mazumdar, Sujit,Barua, Parag D.,Mahajan, Mahinder P.
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p. 315 - 316
(2007/10/02)
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- Derivatives of Imidazolidines from Oxalic Amidines
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Tetraarylsubstituted oxalic amidines 1 react with acyl chlorides, phosgene, thiophosgene, chlorocarbonylsulfenylchloride, isocyaniddichlorides, and N-aroyl-1-chlorothio-formimidoylchlorides 7 to give the corresponding 5-membered heterocycles 3,4,5 and 8.Isocyanates 9 and isothiocyanates 10 react with oxalic amidines to yield imidazolidines 11, 12 and ureas 13, 14.Hydrolysis of 3-5, 8, 11, 12 leads to the corresponding oxo compounds 15, 16.
- Beckert, R.,Mayer, R.
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p. 227 - 236
(2007/10/02)
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- Reactions of N,N-Dialkyl-N'-arylthioureas with α-Haloketones and of 2-Substituted Imino-1,3-oxathioles with Heterocumulenes
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N,N-Dialkyl-N'-arylthioureas react with phenacyl halides to give 2-arylimino-5-phenyl-1,3-oxathioles (I), 3-aryl-2-arylimino-4-phenyl-4-thiazolines (III), aryl isothiocyanates and N,N'-diarylthioureas.I reacts with heterocumulenes like phenyl isocyanate and phenyl isothiocyanate to give 3,4-diaryl-2-arylimino-4-thiazolines, N,N'-diarylthioureas, arylacetylenes and COS or CO2.Mechanisms of formation of the various products have been proposed, based on TLC monitoring at regular time intervals.These are independently supported by chemical reactions.
- Singh, Harjit,Ahuja, A. S.,Malhotra, N.
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p. 1019 - 1022
(2007/10/02)
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- Studies on Aryl- and Diaryl-thioureas and their Insecticidal Activity
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Certain aryl- and diaryl-thioureas having insecticidal activity have been prepared.Their insecticidal property has been evaluated on Sitophilus oryzae (Linn.). 13C NMR spectrum of 1,3-diphenylthiourea has been studied.
- Chatterjee, A.,Das, Biswanath,Adityachaudhury, N.,Kirtaniya, S. Deb
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p. 163 - 164
(2007/10/02)
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