- Preparation of a novel bromine complex and its application in organic synthesis
-
Although molecular bromine (Br2) is a useful brominating reagent, it is not easy to handle. Herein, we describe the preparation of a novel air-stable bromine complex prepared from 1,3-dimethyl-2-imidazolidinone (DMI) and Br2, which was identified to be (DMI)2HBr3 by spectral and X-ray techniques. This complex was then used to brominate olefins, carbonyl compounds, and aromatics, as well as in the Hofmann rearrangement. Yields of reaction products using this complex were almost the same or superior to those using other bromine alternatives.
- Nishio, Yuya,Yubata, Kotaro,Wakai, Yutaro,Notsu, Kotaro,Yamamoto, Katsumi,Fujiwara, Hideki,Matsubara, Hiroshi
-
p. 1398 - 1405
(2019/02/07)
-
- Chemoselective synthesis of carbamates using CO2 as carbon source
-
Synthesis of carbamates directly from amines using CO2 as the carbon source is a straightforward and sustainable approach. Herein, we describe a highly effective and chemoselective methodology for the synthesis of carbamates at room temperature and atmosp
- Riemer, Daniel,Hirapara, Pradipbhai,Das, Shoubhik
-
p. 1916 - 1920
(2018/08/17)
-
- Cu(II)-ion-catalyzed solvolysis of N,N- bis(2-picolyl)ureas in alcohol solvents: Evidence for cleavage involving nucleophilic addition and strong assistance of bis(2-picolyl)amine leaving group departure
-
The kinetics and products for solvolysis of N-p-nitrophenyl-N′, N′-bis(pyridin-2-ylmethyl) urea (7a), N-methyl-N-p-nitrophenyl-N′, N′-bis(pyridin-2-yl methyl) urea (7b), and N-phenyl-N′,N′- bis(pyridin-2-yl-methyl) urea (DPPU) (7c) promoted by Cu(II) ion in methanol and ethanol were studied under sspH-controlled conditions at 25 °C. Methanolysis and ethanolysis of these substrates proceeds rapidly at a 1:1 ratio of substrate:metal ion, the half-times for decomposition of the Cu(II):7a complexes being ~150 min in methanol and 15 min in ethanol. In all cases, the reaction products are the Cu(II) complex of bis(2-picolyl)amine and the O-methyl or O-ethyl carbamate of the parent aniline, signifying that the point of cleavage is the bis(2-picolyl) - N - C - O bond. Reactions of the Cu(II):7b complexes in each solvent proceed about 3-5 times slower than their respective Cu(II):7a complexes, excluding an elimination mechanism that proceeds through an isocyanate which subsequently adds alcohol to give the observed products. The reactions also proceed in other solvents, with the order of reactivity ethanol > methanol >1-propanol >2-propanol > acetonitrile (with 0.2% methanol) > water spanning a range of 150-fold. The mechanism of the reactions is discussed, and the reactivity and mode of cleavage are compared with that of the M(II)-promoted ethanolytic cleavage of a mono-2-picolyl derivative, N-p-nitrophenyl-N′-(pyridin-2-yl-methyl) urea (4a), which had previously been shown to cleave at the aniline N-C - O bond. The large estimated acceleration of the rate of attack of ethoxide on 7b of at least 2 × 1016 provided by associating Cu(II) with the departing group in this urea is discussed in terms of a trifunctional role for the metal ion involving Lewis acid activation of the substrate, intramolecular delivery of a Cu(II)-coordinated ethoxide, and metal-ion-assisted leaving group departure.
- Belzile, Mei-Ni,Neverov, Alexei. A.,Brown, R. Stan
-
p. 7916 - 7925
(2014/08/18)
-
- Novel and efficient one-pot synthesis of (aminophenyl)carbamic acid esters
-
A novel and efficient protocol is developed for the synthesis of various (aminophenyl) carbamic acid esters from the reduction and condensation of nitrophenyl isocyanate derivatives. The reaction takes place in various hydroxy derivatives such as alcohols or phenols under a hydrogen atmosphere using Raney nickel as catalyst. Products are obtained by a convenient one-pot synthesis with excellent yields and short reaction times.
- Garofalo, Antonio,Goossens, Laurence,Six, Perrine,Lebegue, Nicolas,Depreux, Patrick
-
body text
p. 2007 - 2016
(2011/06/24)
-
- New and simple synthesis of acid azides, ureas and carbamates from carboxylic acids: Application of peptide coupling agents EDC and HBTU
-
Conversion of carboxylic acids into acid azides using peptide coupling agents, EDC and HBTU is described. The procedure is efficient, practical and applicable to a diverse range of carboxylic acids including N-protected amino acids. Using the same reagents, one-pot synthesis of ureas, dipeptidyl urea esters and carbamates from acids has also been achieved. The Royal Society of Chemistry 2010.
- Sureshbabu, Vommina V.,Lalithamba,Narendra,Hemantha
-
experimental part
p. 835 - 840
(2010/06/20)
-
- 1-propanephosphonic acid cyclic anhydride (T3P) as an efficient promoter for the Lossen rearrangement: Application to the synthesis of urea and carbamate derivatives
-
The synthesis of hydroxamic acids starting from carboxylic acids employing 1-propanephosphonic acid cyclic anhydride (T3P) activation is described. Application of ultrasonication accelerates this conversion. Further, the T3P has also been employed to activate the hydroxamates, leading to isocyanates via the Lossen rearrangement. The isocyanates were trapped with suitable nucleophiles to afford the corresponding ureas and carbamates. Georg Thieme Verlag Stuttgart New York.
- Vasantha, Basavalingappa,Hemantha, Hosahalli P.,Sureshbabu, Vommina V.
-
experimental part
p. 2990 - 2996
(2010/10/21)
-
- Effect of successive increase in alcohol chains on reaction with isocyanates and isothiocyanates
-
The reaction of isocyanates and isothiocyanates with long-chain alcohols, e.g. n-hexanol, n-heptanol and n-octanol, exclusively gave N-aryl-O-alkyl carbamates, while N-aryl-O-alkyl carbamates were formed along with symmetrical 1,3-disubstituted ureas and thioureas when the same reactions were carried out with small-chain alcohols at room temperature without using any solvent.
- Perveen, Shahnaz,Yasmin, Arfa,Khan, Khalid Mohammed
-
experimental part
p. 18 - 23
(2010/04/23)
-
- Synthesis of some heterocycle containing urea derivatives and their anti-viral activity
-
Some new isoindol heterocyclic ureas (6a-6i) have been synthesized using N-aminophthalimide (2) and ethyl N-monosubstituted/ethyl N,N-disubstituted carbamate (5a-5i). All the newly synthesized final compounds have been evaluated for their anti-viral activities against a variety of viruses. The compound (6f) with the methoxy substituent showed reasonably better activity as compared to the standard drugs against all the viruses (cf. Tables 1, 2 and 3). Further, all the products (6a-6i) were found to be active against Vesicular stomatitis virus, Coxsackie virus B4 and Respiratory syncytical virus (cf. Table 2) and the compounds (6h) and (6i) displayed better antiviral activity in comparison to Brivudin and (S)-DHPA (cf. Table 3).
- Verma, Majusha,Singh, Krishna N.,Clercq, Erik D.
-
-
- A new access to quinazolines from simple anilines
-
A new synthetic pathway to quinazolines is described. This new method uses hexamethylenetetramine in TFA and potassium ferricyanide in aqueous ethanolic KOH, starting from simple N-protected anilines. The method affords substituted quinazolines with high
- Chilin, Adriana,Marzaro, Giovanni,Zanatta, Samuele,Barbieri, Vera,Pastorini, Giovanni,Manzini, Paolo,Guiotto, Adriano
-
p. 12351 - 12356
(2007/10/03)
-
- Synthesis and fungicidal activity of some sulphide derivatives of O-ethyl-N-substituted phenylcarbamates
-
Monosulphides of O-ethyl-N-substituted phenylcarbamates were prepared by the reaction between O-ethyl-N-substituted phenylcarbamates and sulphur dichloride, while the corresponding disulphides were prepared by the reaction between O-ethyl-N-substituted ph
- Adelowo-Imeokparia,Ojo
-
p. 324 - 329
(2007/10/03)
-
- Microwave promoted solvent-free one-pot synthesis of N,N′- disubstituted urea derivatives
-
An efficient one-pot synthesis of N,N′-disubstituted urea derivatives from substituted anilines, ethyl chloroformate and methyl anthranilate or methyl 3-amino-2-butenoate under microwave irradiation is reported.
- Jadhav, Vinod H.,Deshpande, Shubhada S.,Borate, Hanumant B.,Wakharkar, Radhika D.
-
p. 205 - 208
(2007/10/03)
-
- Cyanomethyl anion/carbon dioxide system: An electrogenerated carboxylating reagent. Synthesis of carbamates under mild and safe conditions
-
A new carboxylating reagent (-CH2CN/CO2) was obtained by bubbling CO2 in a CH3CN-TEAP (tetraethylammonium perchlorate) solution previously electrolyzed under galvanostatic control. Organic carbamates were isolated from these solutions after addition of amines and an alkylating agent. In this paper, we describe the optimized conditions for the electrochemical synthesis of carbamates from amines and CO2, in mild and safe conditions, without any addition of bases, probases, or catalysts. Carbamates were isolated from primary and secondary aliphatic amines in high to excellent yields and from aromatic amines in moderate yields (dependent on the nucleophilicity of the nitrogen atom).
- Feroci, Marta,Casadei, Maria Antonietta,Orsini, Monica,Palombi, Laura,Inesi, Achille
-
p. 1548 - 1551
(2007/10/03)
-
- Synthesis of Carbamates Using Yttria-Zirconia Based Lewis Acid Catalyst
-
A variety of amines react with chloroformates in the presence of catalytic amount of yttria-zirconia based catalyst to afford the corresponding carbamates in excellent yields.
- Pandey, Rajesh K.,Dagade, Sharda P.,Dongare, Mohan K.,Kumar, Pradeep
-
p. 4019 - 4027
(2007/10/03)
-
- Preparation and applications of a polymer-supported phosphoryl azide
-
A polymer-supported diphenylphosphoryl azide was prepared. This polymer-supported version of DPPA is useful due to its lower toxicity, moisture tolerance and ease of workup after reaction. The synthetic application of this solid-phase reagent was explored by conversion of a variety of carboxylic acids to urethanes and ureas through Curtius rearrangement reactions. Carboxylic acids bearing different functional groups (aromatic, aliphatic and heterocyclic carboxylic acids) were subjected to the reaction. The corresponding products were isolated with satisfactory yields.
- Lu, Yuhua,Taylor, Richard T.
-
p. 9267 - 9269
(2007/10/03)
-
- Synthesis of alkyl N-(C-nitrosoaryl)carbamates and some reactions thereof
-
Reactions of alkyl N-phenylcarbamates, m-di(methoxycarboxyamido)benzene, and methyl N-(o-tolyl)carbamate with nitrosylsulfuric acid in glacial acetic acid afford N-(C-nitrosoaryl)carbamates; under these conditions tert-bulyl N-phenylcarbamate suffers decarboxylation, methyl N-(p-tolyl)-, methyl N-(p-methoxyphenyl)carbamates, o-and p-di(methoxycarboxyamido)benzenes are nitrated, and isomeric methyl N-nitrophenylcarbamates and methyl N-(p-bromophenyl)carbamate do not react. The reduction of N-(C-nitrosoaryl)carbamates with dithionite afforded the corresponding aminocarbamates; the oxidation with nitric acid yielded carbamate nitro derivatives; the condensation with aniline and benzylpyridinium chloride resulted in carbamate derivatives of azobenzene and phenylnitron.
- Velikorodov
-
p. 233 - 239
(2007/10/03)
-
- The reaction of amines with an electrogenerated base. Improved synthesis of arylcarbamic esters
-
The electrogenerated base of 2-pyrrolidone reacts with amines and anilines yielding the corresponding alkyl and aryl carbamates, after addition of carbon dioxide and ethyl iodide. Arylcarbamic esters are obtained in very good yields under mild reaction conditions with respect to the methods so far reported. (C) 2000 Elsevier Science Ltd.
- Feroci, Marta,Inesi, Achille,Rossi, Leucio
-
p. 963 - 966
(2007/10/03)
-
- Indium-mediated efficient conversion of azides to carbamates
-
A novel and efficient method for the high yield preparation of carbamates by the reaction of azides with several chloroformates using indium metal in DMF at ambient temperature is described for the first time.
- Yadav,Subba Reddy,Kiran Kumar Reddy
-
p. 571 - 573
(2007/10/03)
-
- Piperidine derivatives with PAF antagonist activity
-
Compounds of general formula I and their salts and solvates are PAF antagonists and as such are useful in the treatment of various diseases or disorders mediated by PAF. Pharmaceutical compositions including these compounds and processes for their prepara
- -
-
-
- Method for treating swine dysentery with the derivatives of the antibiotic A82810
-
New polyether antibiotic A82810, its acyl and alkyl ester, acyl ester and urethane derivatives, and salts thereof, are useful antibacterial and anticoccidial agents and increase feed-utilization efficiency in animals. Methods of making A82810 by culture of Actinomodura fibrosa sp. nov. NRRL 18348 and synergistic compositions of the A82810 compounds with nicarbazin, 4,4'-dinitrocarbanilide, certain napthalenamine and benzenamine compounds and metichlorpindol are also provided.
- -
-
-
- A simple method for the synthesis of carbamates
-
A new method for carbamate synthesis using aryl and alkylamines with sodium hydride and diethylcarbonate in dry benzene is described.
- Angeles,Santillan,Martinez,Ramirez,Moreno,Salmon,Martinez
-
p. 2441 - 2447
(2007/10/02)
-
- Kinetics of the Mercury(II) Ion-promoted Desulfurisation of Thiocarbamates in Aqueous Solution
-
In a 1percent dioxane-water solvent in the presence of Hg2+ ions thiocarbamates p-RC6H4NHC(S)OEt (R = MeO, Me, H, F) rapidly form complexes of 2 thiocarbamate: 1 Hg2+ stoichiometry.In the presence of an excess of Hg2+ ions partial conversion to the 2:2-complexes probably occurs which decompose to the corresponding carbamates (p-RC6H4NHCO2Et) and HgS.With R = NO2 the 2:2 complex is dominant even at low Hg2+ ion concentrations, and desulfurisation is then independent of 2+>.Electron-withdrawal by R favours the 2:2 complex but decreases its rate of decomposition to products.The effects of changes in the hydrogen ion concentration suggest that ionisation of N-bound protons in the complexes favours reaction.A mechanism is suggested.The kinetic behaviour is somewhat similar to that found previously for thiobenzamides, but the new results suggest the mechanism previously proposed may need revision.
- Satchell, Derek P. N.,Satchell, Rosemary S.,Wassef, Wasfy N.
-
p. 1091 - 1094
(2007/10/02)
-
- A Comparison of the Reactions of Some Ethyl N-Arylcarbamates with Those of the Corresponding Acetanilides. I. Nitration
-
The reactions of some ethyl N-arylcarbamates and of the corresponding acetanilides towards 1 equiv. of sodium nitrate in concentrated sulfuric acid at 0-5 deg have been compared with one another and have been found to exhibit significant differences.Except in the case of the unsubstituted analogues, nitration of the carbamates was found to occur significantly more quickly than that of the acetanilides as shown by (i) a representative competitive nitration, and (ii) the fact the carbamates containing a nitro group are nitrated smoothly whereas the corresponding nitroacetanilides are slow to react.On the basis of competitive reactions, it is suggested that this difference in reactivity is due to steric factors.
- Rosevear, Judi,Wilshire, John F. K.
-
p. 723 - 733
(2007/10/02)
-
- Formation of Isocyanates by Deoxygenation of C-Nitrosocarbonyl Compounds
-
The cycloadduct (1a) of 9,10-dimethylanthracene (2) (hereinafter referred to as DMA) and nitrosocarbonylbenzene decomposed in benzene at 80 deg C in the presence of triphenylphosphine to give DMA, triphenylphosphine oxide, and phenyl isocyanate in high yield.The corresponding adducts of 4-chloro-(1b), 4-methoxy-(1c), and 4-nitro-nitrosocarbonylbenzene (1d) behaved likewise.The cycloadduct of DMA and 4-methoxybenzylnitrosocarbonylmethane (1e) and of DMA and 1-(4-methoxyphenyl)-2-nitrosocarbonylethane (1f) gave lower (20-30 percent) yields of isocyanates.The rates of decomposition of the adduct (1a) in the presence of either the conjugated diene thebaine (3) or various phosphorus(III) derivatives were the same within experimental error.A similar observation was made for compound (1d).The formation of isocyanates is believed to involve slow dissociation of the cycloadducts followed by rapid deoxygenation of the transient nitrosocarbonyl compounds by triphenylphosphine.Stable complexes (8) of triphenylphosphine oxide with N-(4-nitrophenyl)-N'-propylurea and N-(4-nitrophenyl)-N'-phenylurea are described.
- Corrie, John E.T.,Kirby, Gordon W.,Sharma, Ram P.
-
p. 1571 - 1574
(2007/10/02)
-