- Nickel-Catalyzed Synthesis of N-(Hetero)aryl Carbamates from Cyanate Salts and Phenols Activated with Cyanuric Chloride
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A simple and efficient domino reaction has been designed and employed for the one-pot synthesis of N-(hetero)aryl carbamates through the reaction between alcohols and in-situ produced (hetero)aryl isocyanates in the presence of a nickel catalyst. The phenolic C?O bond was activated via the reaction of phenol with cyanuric chloride (2,4,6-trichloro-1,3,5-triazine (TCT)) as an inexpensive and readily available reagent. This strategy provides practical access to N-(hetero)aryl carbamates in good yields with high functional groups compatibility.
- Dindarloo Inaloo, Iman,Esmaeilpour, Mohsen,Majnooni, Sahar,Reza Oveisi, Ali
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p. 5486 - 5491
(2020/09/04)
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- A Fe3O4?SiO2/Schiff Base/Pd Complex as an Efficient Heterogeneous and Recyclable Nanocatalyst for One-Pot Domino Synthesis of Carbamates and Unsymmetrical Ureas
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A palladium-catalyzed domino method for the direct synthesis of carbamates and ureas has been developed by using readily available and economical starting materials (aryl halide, carbon monoxide, sodium azide, amines and alcohols) in a one-pot approach. The domino process underwent carbonylation, Curtius rearrangement, and nucleophilic addition. This protocol provides a step-economical and highly efficient reaction to access the wide range of valuable carbamates, symmetrical and unsymmetrical ureas with high yields under remarkable mild reaction conditions that are important factors in pharmaceutical science, biochemistry and agricultural industries. Furthermore, the magnetically recoverable nanocatalyst (Fe3O4?SiO2/Pd(II)) can be conveniently and swiftly recycled using external magnet and reused at least for seven times without noticeable loss of its catalytic activity.
- Inaloo, Iman Dindarloo,Majnooni, Sahar
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p. 6359 - 6368
(2019/11/05)
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- Carbon dioxide utilization in the efficient synthesis of carbamates by deep eutectic solvents (DES) as green and attractive solvent/catalyst systems
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A green and eco-friendly solvent/catalyst system based on a deep eutectic solvent (DES) was devised and developed for the simple synthesis of carbamates through three-component coupling of amines, alkyl halides and carbon dioxide (CO2). It was found that choline chloride:zinc(ii) chloride ([ChCl][ZnCl2]2) was very proficient and effective for the activation and utilization of CO2 in carbamate formation reactions from a wide scope of amines. Surprisingly, this strategy provides the desired carbamates under atmospheric CO2 pressure at room temperature. In particular, both aromatic and aliphatic amines were effective and demonstrated excellent yields. Besides, the [ChCl][ZnCl2]2 exhibited very high stability and also could be reused for at least five consecutive cycles without any significant loss of activity. It is worth noting that this is the first solvent/catalyst system which can be recycled successfully from the reaction mixture.
- Dindarloo Inaloo, Iman,Majnooni, Sahar
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p. 11275 - 11281
(2019/07/31)
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- Ureas as safe carbonyl sources for the synthesis of carbamates with deep eutectic solvents (DESs) as efficient and recyclable solvent/catalyst systems
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A simple, efficient and eco-friendly one-pot synthesis of primary, N-mono- and N-disubstituted carbamates is developed from ureas. The corresponding carbamates were produced at 120 °C, within 18 h, and in the presence of a deep eutectic solvent as a recyclable catalytic system. The catalyst can be reused for several runs without any reduction in its activity. To demonstrate the utility of this approach, a wide variety of alcohols and phenols were studied to find a vast range of carbamate derivatives in moderate to high yields.
- Dindarloo Inaloo, Iman,Majnooni, Sahar
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p. 13249 - 13255
(2018/08/21)
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- Direct Catalytic Synthesis of N-Arylcarbamates from CO2, Anilines and Alcohols
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The direct catalytic synthesis of carbamates from CO2, amines and methanol was achieved by controlling both the reaction equilibrium and the reactivity of the three components. The combination of CeO2 and 2-cyanopyridine was an effective catalyst, providing various carbamates including N-arylcarbamates in high selectivities.
- Tamura, Masazumi,Miura, Ayaka,Honda, Masayoshi,Gu, Yu,Nakagawa, Yoshinao,Tomishige, Keiichi
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p. 4835 - 4839
(2018/10/15)
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- METHOD FOR PRODUCING CARBAMATE
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PROBLEM TO BE SOLVED: To provide a method for producing carbamate in which a high yield can be obtained and the amount of by-products produced can be reduced. SOLUTION: In the method, carbamate is synthesized using at least one member selected from the group consisting of amine and derivative thereof, alcohol having 3 or more carbon atoms and carbon dioxide as a raw material, cerium oxide as a catalyst, and 2-cyanopyridine as a dehydrating agent. By using an alcohol having 3 or more carbon atoms, a high yield can be obtained and the amount of by-products produced can be reduced. In addition, the pressure of carbon dioxide can be lowered and the production can be of ease. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2018,JPO&INPIT
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Paragraph 0041; 0043
(2018/10/16)
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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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- One-pot synthesis of carbamates and thiocarbamates from Boc-protected amines
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A highly efficient one-pot procedure for the synthesis of carbamates and thiocarbamates has been described. In the presence of 2-chloropyridine and trifluoromethanesulfonyl anhydride, the isocyanate intermediates were generated in situ for further reactions with alcohols and thiols to afford the desired carbamates and thiocarbamates in high yields.
- Kim, Hee-Kwon,Lee, Anna
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supporting information
p. 4890 - 4892
(2016/10/21)
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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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- A synthetic approach to N -aryl carbamates via copper-catalyzed Chan-Lam coupling at room temperature
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A mild and efficient synthesis of N-arylcarbamates was achieved by reacting azidoformates with boronic acids in the presence of 10 mol % of copper chloride catalyst. The reaction proceeds readily in an open flask at room temperature without additional base, ligand, or additive. Rapid access to urea analogues via a two-step one-pot procedure is enabled by reacting N-arylcarbamates with aluminum-amine complexes. In addition, among several boronic acid derivatives prepared, dimethylphenyl boronate was found to react rapidly in its reaction with benzyl azidoformate, invoking in situ generation of this species in the catalytic cycle.
- Moon, Soo-Yeon,Kim, U. Bin,Sung, Dan-Bi,Kim, Won-Suk
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p. 1856 - 1865
(2015/02/19)
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- Reaction of organozinc halides with aryl isocyanates
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Reformatsky reagent, benzylzinc bromide or alkylzinc iodides react with aryl isocyanates directly to give corresponding N-substituted carbamates under mild reaction conditions. However, the reaction of allylzinc bromide or propargylzinc bromide with aryl isocyanates produces the corresponding N-substituted amides. The reactions provide alternative methods for the synthesis of N-substituted carbamates or amides.
- Yang, Haoran,Huang, Danfeng,Wang, Ke-Hu,Xu, Changming,Niu, Teng,Hu, Yulai
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supporting information
p. 2588 - 2593
(2013/03/28)
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- Mechanistic investigation of oxidative Mannich reaction with tert-butyl hydroperoxide. the role of transition metal salt
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A general mechanism is proposed for transition metal-catalyzed oxidative Mannich reactions of N,N-dialkylanilines with tert-butyl hydroperoxide (TBHP) as the oxidant. The mechanism consists of a rate-determining single electron transfer (SET) that is uniform from 4-methoxy- to 4-cyano-N,N-dimethylanilines. The tert-butylperoxy radical is the major oxidant in the rate-determining SET step that is followed by competing backward SET and irreversible heterolytic cleavage of the carbon-hydrogen bond at the α-position to nitrogen. A second SET completes the conversion of N,N-dimethylaniline to an iminium ion that is subsequently trapped by the nucleophilic solvent or the oxidant prior to formation of the Mannich adduct. The general role of Rh2(cap) 4, RuCl2(PPh3)3, CuBr, FeCl 3, and Co(OAc)2 in N,N-dialkylaniline oxidations by T-HYDRO is to initiate the conversion of TBHP to tert-butylperoxy radicals. A second pathway, involving O2 as the oxidant, exists for copper, iron, and cobalt salts. Results from linear free-energy relationship (LFER) analyses, kinetic and product isotope effects (KIE and PIE), and radical trap experiments of N,N-dimethylaniline oxidation by T-HYDRO in the presence of transition metal catalysts are discussed. Kinetic studies of the oxidative Mannich reaction in methanol and toluene are also reported.
- Ratnikov, Maxim O.,Doyle, Michael P.
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supporting information
p. 1549 - 1557
(2013/03/14)
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- PROCESS FOR PREPARING ISOCYANATES
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Process for preparing aromatic isocyanates by reacting the corresponding formamides with an oxygen-comprising gas over noble metal catalysts at temperatures of from 300 to 600° C. and a contact time of from 1 to 1000 ms, wherein: a. the formamide is vapor
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Page/Page column 4
(2012/10/08)
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- Kinetics and Mechanism of Isocyanate Reactions. II. Reactions of Aryl Isocyanates with Alcohols in the Presence of Tertiary Amines
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The reaction of phenyl isocyanate with n-butanol in the presence of tertiary amines has been kinetically studied as a model process for the polyurethane formation under conditions similar to those of industrial scale production.The rate-determining step is belived to be the nucleophilic attack of tertiary amine on an associate of isocyanate with alcohol which is then converted into a very reactive uronium salt.This salt reacts fast with alcohol giving the final product, the urethane.
- Bacaloglu, R.,Cotarca, L.,Marcu, N.,Toelgyi, St.
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p. 530 - 540
(2007/10/02)
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- Kinetics and Mechanism of Isocyanate Reactions. III. Reactions of Aryl Isocyanates with Alcohols in the Presence of Organotin Compounds
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A comparative kinetic study for the reaction of aryl isocyanates with alcohols in the presence of organotin compounds has been performed.It has been found that the transfer of an alkoxide ion from tin to isocyanate is the rate-determining step.This transfer occurs within a complex formed in two rapid preequilibrium processes between either tin compounds and alcohol or isocyanate, respectively.
- Bacaloglu, R.,Cotarca, L.,Marcu, N.,Toelgyi, St.
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p. 541 - 548
(2007/10/02)
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- Reactions of Aryl Isocyanates with Alcohols
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The reaction of aryl isocyanates with alcohols has been kinetically studied as a model reaction for polyurethane formation under conditions similar to those of industrial scale production.Considering the isocyanate and alcohol structure, kinetic isotopic effect, activation enthalpy and entropy and solvent effects it has been found that the most probable mechanism is the alcohol addition through a four-membered cyclic transition state.
- Bacaloglu, R.,Cotarca, L.,Marcu, N.,Toelgyi, St.
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p. 428 - 434
(2007/10/02)
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- Process for preparing polymethylene-polyphenyl polyisocyanates
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A process for preparing polymethylene polyphenyl polyisocyanates, in which N-phenyl carbamic acid esters are subjected to a condensation reaction with formaldehyde, and the reaction product containing polymethylene polyphenyl polycarbamic acid esters and unreacted N-phenyl carbamic acid esters is thermally decomposed to obtain polymethylene polyphenyl polyisocyanates.
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