- Silica supported perchloric acid (HClO4-SiO2): an efficient reagent for the preparation of primary carbamates under solvent-free conditions
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The synthesis of primary carbamates from structurally diverse compounds containing a hydroxyl group has been performed in high yields and purity, and without any epimerization under solvent-free conditions using HClO4-SiO2 as a mild, convenient, and effective reagent. The procedure is operationally simple, efficient, and environmentally benign.
- Modarresi-Alam, Ali Reza,Khamooshi, Ferydoon,Nasrollahzadeh, Mahmoud,Amirazizi, Homeyra Alsadat
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- An efficient one-pot synthesis of industrially valuable primary organic carbamates and: N -substituted ureas by a reusable Merrifield anchored iron(ii)-anthra catalyst [FeII(Anthra-Merf)] using urea as a sustainable carbonylation source
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An efficient synthesis of primary carbamates and N-substituted ureas is explored with a newly developed heterogeneous polymer supported iron catalyst in the presence of a sustainable carbonylation source. The Merrifield anchored iron(ii)-anthra catalyst [FeII(Anthra-Merf)] was synthesized by functionalization of Merrifield polymer followed by grafting of iron metal. The catalyst [FeII(Anthra-Merf)] was characterized by several techniques, like SEM, EDAX, TGA, PXRD, XPS, FTIR, CHN, AAS and UV-Vis analysis. The designed polymer embedded [FeII(Anthra-Merf)] complex is a remarkably successful catalyst for the synthesis of primary organic carbamates and N-substituted ureas by using safe carbonylation agent urea with different derivatives of alcohols and amines, respectively. The reported catalyst is a potential candidate towards contributing a satisfactory yield of isolated products under suitable reaction conditions. The catalyst is recyclable and almost non-leaching in nature after six runs with an insignificant drop in catalytic activity. Thus we found an economical and viable catalyst [FeII(Anthra-Merf)] for primary carbamates and N-substituted urea synthesis under moderate reaction conditions.
- Basu, Priyanka,Dey, Tusar Kanto,Ghosh, Aniruddha,Biswas, Surajit,Khan, Aslam,Islam, Sk. Manirul
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- Indium(III)-Catalyzed Synthesis of Primary Carbamates and N-Substituted Ureas
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An indium triflate-catalyzed synthesis of primary carbamates from alcohols and urea as an ecofriendly carbonyl source has been developed. Various linear, branched, and cyclic alcohols were converted into the corresponding carbamates in good to excellent yields. This method also provided access to N-substituted ureas by carbamoylation of amines. All the products were obtained by simple filtration or crystallization, without the need for chromatographic purification. Mechanistic investigations suggest that the carbamoylation reaction proceeds through activation of urea by O-coordination with indium, followed by nucleophilic attack by the alcohol or amine on the carbonyl center of urea. The inexpensive and easily available starting materials and catalyst, the short reaction times, and the ease of product isolation highlight the inherent practicality of the developed method.
- Jain, Isha,Malik, Payal
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supporting information
p. 93 - 97
(2021/11/26)
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- An Fe3O4@SiO2/Schiff base/Cu(ii) complex as an efficient recyclable magnetic nanocatalyst for selective mono: N-arylation of primary O-alkyl thiocarbamates and primary O-alkyl carbamates with aryl halides and arylboronic acids
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An efficient, convenient and novel method for the selective mono N-arylation of primary O-alkyl thiocarbamates and primary O-alkyl carbamates with aryl halides and arylboronic acids in the presence of a recyclable magnetic Cu(ii) nanocatalyst is described. A variety of mono N-arylated O-alkyl thiocarbamates and O-alkyl carbamates were prepared in good to excellent yields with a broad range of aryl coupling partners. The magnetic nanocatalyst can be easily recovered with an external magnetic field and reused at least five times without noticeable leaching or loss of its catalytic activity. This cost-effective and eco-friendly methodology has some other advantages, such as easy preparation of the catalyst, simple workup procedure, and easy purification, which makes this protocol interesting for the users in various fields of pharmacology and biotechnology systems.
- Sardarian, Ali Reza,Dindarloo Inaloo, Iman,Zangiabadi, Milad
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p. 8557 - 8565
(2019/06/14)
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- Superparamagnetic Fe3O4 Nanoparticles in a Deep Eutectic Solvent: An Efficient and Recyclable Catalytic System for the Synthesis of Primary Carbamates and Monosubstituted Ureas
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Superparamagnetic Fe3O4 nanoparticles were used to synthesize various primary carbamates as well as monosubstituted and N,N-disubstituted ureas. This efficient phosgene-free process used urea as an eco-friendly carbonyl source in the presence of a biocompatible deep eutectic solvent (DES) to provide an inexpensive and attractive route that afforded the products in moderate to excellent yields. The employed DES serves both a catalytic role and as the green reaction medium. The magnetic nanocatalyst and DES can been reused several times without a significant loss of activity.
- Inaloo, Iman Dindarloo,Majnooni, Sahar,Esmaeilpour, Mohsen
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p. 3481 - 3488
(2018/07/29)
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- Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective Copper-Catalyzed Mono Arylation of Primary Carbamates with Aryl Halides and Arylboronic Acids
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Abstract: An efficient, selective and cost-effective procedure has been developed for mono N-arylation of primary alkyl and benzyl carbamates with aryl iodides and bromides by incorporating CuI as an inexpensive and commercially available catalyst. Despite previous reports on C–N coupling reactions, this process does not need expensive ligands and takes advantage of readily available and inexpensive ethylenediamine (EDA) as the ligand. Reaction times were relatively short and related N-arylated carbamates were obtained in excellent yields. Interestingly, replacing CuI with Cu(OAc)2 allowed us to use arylboronic acids as coupling partner for this reaction. All products are well characterized by 1H- and 13C-NMR, MS, melting point, IR and CHNS techniques.
- Sardarian, Ali Reza,DindarlooInaloo, Iman,Zangiabadi, Milad
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p. 642 - 652
(2018/01/11)
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- Iron-catalyzed reaction of urea with alcohols and amines: A safe alternative for the synthesis of primary carbamates
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A general study of the iron-catalyzed reaction of urea with nucleophiles is here presented. The carbamoylation of alcohols allows for the synthesis of N-unsubstituted (primary) carbamates, including present drugs (Felbamate and Meprobamat, without the necessity to apply phosgene and related derivatives. Using amines as nucleophiles gave rise to the respective mono-and disubstituted ureas via selective transamidation reaction. These atom-economical transformations provide a direct and selective access to valuable compounds from cheap and readily available urea using a simple Lewis-acidic iron(Icatalyst.
- Pe?a-López, Miguel,Neumann, Helfried,Beller, Matthias
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p. 2233 - 2238
(2017/07/25)
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- Fe3O4@SiO2/Schiff base/Pd complex as an efficient heterogeneous and recyclable nanocatalyst for chemoselective: N -arylation of O -alkyl primary carbamates
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An efficient, heterogeneous and cost effective method has been developed using an Fe3O4@SiO2/Schiff base/Pd complex as a magnetic and easily recyclable nanocatalyst for rapid and effective N-arylation of carbamates in good to excellent yield. The catalyst can be easily recovered and reused over six runs without significant decrease in the activity. Further highlights of this protocol are operational simplicity, versatility and relatively short reaction times.
- Sardarian,Zangiabadi,Inaloo, I. Dindarloo
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p. 92057 - 92064
(2016/10/11)
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- 4-Dodecylbenzenesulfonic acid (DBSA) promoted solvent-free diversity-oriented synthesis of primary carbamates, S-thiocarbamates and ureas
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A simple and highly efficient solvent-free method for the conversion of alcohols, phenols, thiols and amines to primary carbamates, S-thiocarbamates and ureas in the presence of 4-dodecylbenzenesulfonic acid (DBSA) as a cheap and green Bronsted acid reagent has been described. All products were obtained in good to excellent yields and characterized using FT-IR, 1H- and 13C-NMR, MS and CHNS techniques.
- Sardarian, Ali Reza,Inaloo, Iman Dindarloo
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p. 76626 - 76641
(2015/09/22)
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- Thiophene S,N-Ylides: A New Versatile Class of Sulphimides
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Tetrachlorothiophene reacts with methyl, ethyl, and phenyl azidoformates and with toluene-p-sulphonyl azide at 130-150 deg C to give stable thiophene S,N-ylides. 2,5-Dichloro and 2,5-dibromo-thiophene and tetrabromothiophene yield products derived by nitrene attack at the α-position.The S,N-ylides undergo ready photolysis to liberate the parent nitrene, and react with a wide variety of electron-rich dienophiles as 4?-components to give tetrachlorodihydrobenzenes with extrusion of a thionitroso compound.With dienes the ylides react either as 2?- or 4?-systems.Thus with anthracene a dihydrothiophene analogue of triptycene is generated efficiently aromatised and de-ylidated with zinc in methanol.With dimethyl acetylenedicarboxylate the ylides yield a thiazocine by a novel ring expansion.Oxidation of the ylide system with 3-chloroperbenzoic acid gives the corresponding ylide S-oxide.Tetrachlorothiophene also reacts efficiently with diazoalkanes under rhodium acetate catalysis to give thiophene S,C-ylides, which undergo cycloaddition with nucleophilic alkenes much more slowly than their nitrogen analogues.
- Meth-Cohn, Otto,Vuuren, Gerda van
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p. 233 - 244
(2007/10/02)
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