- N-Aryl and N-Alkyl Carbamates from 1 Atmosphere of CO2
-
We have successfully isolated and characterized the zinc carbamate complex (phen)Zn(OAc)(OC(=O)NHPh) (1; phen=1,10-phenanthroline), formed as an intermediate during the Zn(OAc)2/phen-catalyzed synthesis of organic carbamates from CO2, amines, and the reusable reactant Si(OMe)4. Density functional theory calculations revealed that the direct reaction of 1 with Si(OMe)4 proceeds via a five-coordinate silicon intermediate, forming organic carbamates. Based on these results, the catalytic system was improved by using Si(OMe)4 as the reaction solvent and additives like KOMe and KF, which promote the formation of the five-coordinated silicon species. This sustainable and effective method can be used to synthesize various N-aryl and N-alkyl carbamates, including industrially important polyurethane raw materials, starting from CO2 under atmospheric pressure.
- Chen, Ming-Yu,Choe, Yoong-Kee,Choi, Jun-Chul,Fukaya, Norihisa,Hamura, Satoshi,Koizumi, Hiroki,Matsumoto, Kazuhiro,Matsumoto, Seiji,Shigeyasu, Shinji,Takeuchi, Katsuhiko,Yuan, Hao-Yu
-
supporting information
p. 18066 - 18073
(2021/12/08)
-
- Methoxycarbonylation of Alkyl-, Cycloalkyl-, and Arylamines with Dimethyl Carbonate in the Presence of Binder-Free Zeolite
-
Abstract: Methyl N-alkyl-, N-cycloalkyl-, and N-arylcarbamates were synthesized by reaction of the correspondingamines with dimethyl carbonate in the presence of binder-free FeHY zeolite. Theoptimal conditions (reactant ratio, amount of the catalyst, temperature,reaction time) were found to afford the target products with high yields.
- Khazipova, A. N.,Khusnutdinov, R. I.,Mayakova, Yu. Yu.,Shchadneva, N. A.
-
p. 1228 - 1235
(2020/10/02)
-
- 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)
-
- PRODUCTION METHOD OF CARBAMIC ACID ESTER
-
A method of production of carbamic acid ester has a high yield and high selectivity and is superior in economy. The method of production of a carbamic acid ester includes reacting an amine, carbon dioxide, and an alkoxysilane compound in the presence of a catalyst containing a zinc compound or an alkali metal compound or in the presence of an ionic liquid. A carbamic acid ester is produced, for example by reacting aniline, carbon dioxide, and tetramethoxysilane at a temperature of 150 to 180° C. in the presence of zinc acetate and 2,2′-bipyridine.
- -
-
Paragraph 0048; 0050
(2019/07/03)
-
- Phosgene-free synthesis of carbamates using co2 and titanium alkoxides
-
A facile one-pot, phosgene-free method for the synthesis of N-phenylcarbamates is developed. Using this method, various aromatic carbamates could be prepared from aromatic amines, CO2 and metal alkoxides. Aniline reacted with titanium methoxide (Ti(OMe)4)) in the presence of CO2 (5 MPa) to give methyl N-phenylcarbamate in 85% yield, in 20min. Titanium residue could be regenerated by reaction with dimethyl carbonate at 220 °C for 16 h.
- Yuan, Hao-Yu,Zhang, Qiao,Fukaya, Norihisa,Lin,Fujitani, Tadahiro,Choi, Jun-Chul
-
p. 1481 - 1486
(2018/10/25)
-
- Metal-Free Synthesis of Unsymmetrical Ureas and Carbamates from CO2 and Amines via Isocyanate Intermediates
-
A mild and metal-free synthesis of aryl isocyanates from arylamines under an atmosphere of CO2 was developed. The carbamic acid intermediate, derived from the arylamine starting material and CO2 in the presence of DBU, is dehydrated by activated sulfonium reagents to generate the corresponding isocyanate. The latter can be detected by in situ IR and trapped by various amines and alcohols to make unsymmetrical ureas and carbamates, respectively. Dicarbamates can also be prepared in good yields via the mild dehydration of the corresponding dicarbamic acids.
- Ren, Yiming,Rousseaux, Sophie A. L.
-
p. 913 - 920
(2018/01/28)
-
- Direct synthesis of carbamate from CO2 using a task-specific ionic liquid catalyst
-
A superbase-derived protic ionic liquid (IL, [DBUH][OAc]) catalyst was used to directly synthesize carbamate from an amine, CO2, and a silicate ester. This IL catalyst was easily prepared using its precursors, DBU, and acetic acid. Using 10 mol% of the catalyst under a CO2 pressure of 5 MPa in acetonitrile at 150 °C, carbamate was isolated in up to 96% yield. Specifically, aliphatic and aromatic amines were activated even though aromatic amines exhibited low activities because of their low pKa values. Other functional groups in amines were barely activated, affording exclusive chemoselectivity for amine activation. Isotope labeling experiments indicated that the proton in the counter cation is crucial in the catalytic cycle to produce water. In addition, a chemical shift corresponding to a mixture of aniline and [DBUH][OAc] was observed in the 1H NMR spectrum, related to the formation of hydrogen bonds between aniline and basic acetate anions. The experimental results indicated that the designed IL catalysts require a protonated cation and a basic anion.
- Zhang, Qiao,Yuan, Hao-Yu,Fukaya, Norihisa,Yasuda, Hiroyuki,Choi, Jun-Chul
-
p. 5614 - 5624
(2017/12/06)
-
- A Simple Zinc Catalyst for Carbamate Synthesis Directly from CO2
-
Several zinc salts were employed as catalysts for the synthesis of carbamates directly from aromatic amines, CO2, and silicate esters. Zn(OAc)2 offered the best performance among the salts tested. The addition of an N-donor ligand such as 1,10-phenanthroline increased the yield. The best catalytic performance of Zn(OAc)2 can be explained by carboxylate-assisted proton activation. The interaction between the substrate and the catalyst can be observed by chemical shifts in 1H and 15N NMR spectra. Isocyanate was a key intermediate, which was generated from amine and CO2. Silicate ester was finally converted to siloxane, which was determined by 29Si NMR. The commercially available catalyst system could be reused. The yield of isolated carbamate could reach up to 96 % with various substrates, and the catalytic reaction was amine-selective in the presence of other functional groups.
- Zhang, Qiao,Yuan, Hao-Yu,Fukaya, Norihisa,Yasuda, Hiroyuki,Choi, Jun-Chul
-
p. 1501 - 1508
(2017/04/14)
-
- Synthesis of carbamates from carbon dioxide promoted by organostannanes and alkoxysilanes
-
A cooperative methoxy transfer between orthosilicate esters and organotin oxides was developed for the synthesis of various N-alkyl and N-aryl carbamates from carbon dioxide in up to 97% isolated yield. The reaction is highly selective and N-alkylated amines are not observed. Density functional theory calculations of the reaction were performed and, together with NMR observations, a plausible mechanism featuring the catalytic regeneration of dialkyltin dialkoxide is proposed.
- Germain, Nicolas,Hermsen, Marko,Schaub, Thomas,Trapp, Oliver
-
-
- N-Methylation of poorly nucleophilic aromatic amines with dimethyl carbonate
-
Abstract: Dimethyl carbonate (DMC), an environmentally friendly methylation agent, is a substitute for traditional methylation agents such as methyl halides (CH3X, X?=?I, Br, Cl) or dimethyl sulfate. An efficient, convenient, and green method has been developed for N-methylation of poorly nucleophilic aromatic amines with DMC. It was found that the couple PEG400/K2CO3 provides good selectivity for the N-methylation product. Finally, the mechanism for reaction of amines with DMC was investigated, and a plausible multistep mechanism proposed and verified. Graphical Abstract: [Figure not available: see fulltext.]
- Yan, Huidong,Zeng, Liufang,Xie, Yaqiang,Cui, Yu,Ye, Liyi,Tu, Song
-
p. 5951 - 5960
(2016/06/01)
-
- Discovery and Structure-Based Optimization of 2-Ureidothiophene-3-carboxylic Acids as Dual Bacterial RNA Polymerase and Viral Reverse Transcriptase Inhibitors
-
We are concerned with the development of novel anti-infectives with dual antibacterial and antiretroviral activities for MRSA/HIV-1 co-infection. To achieve this goal, we exploited for the first time the mechanistic function similarity between the bacterial RNA polymerase (RNAP) "switch region" and the viral non-nucleoside reverse transcriptase inhibitor (NNRTI) binding site. Starting from our previously discovered RNAP inhibitors, we managed to develop potent RT inhibitors effective against several resistant HIV-1 strains with maintained or enhanced RNAP inhibitory properties following a structure-based design approach. A quantitative structure-activity relationship (QSAR) analysis revealed distinct molecular features necessary for RT inhibition. Furthermore, mode of action (MoA) studies revealed that these compounds inhibit RT noncompetitively, through a new mechanism via closing of the RT clamp. In addition, the novel RNAP/RT inhibitors are characterized by a potent antibacterial activity against S. aureus and in cellulo antiretroviral activity against NNRTI-resistant strains. In HeLa and HEK 293 cells, the compounds showed only marginal cytotoxicity.
- Elgaher, Walid A. M.,Sharma, Kamal K.,Haupenthal, J?rg,Saladini, Francesco,Pires, Manuel,Real, Eleonore,Mély, Yves,Hartmann, Rolf W.
-
supporting information
p. 7212 - 7222
(2016/08/24)
-
- Palladium-Catalyzed Carbamate-Directed Regioselective Halogenation: A Route to Halogenated Anilines
-
This study describes an efficient method for ortho-selective halogenation of N-arylcarbamates under mild conditions for the first time. Although being weakly coordinating, N-arylcarbamates act very well as a removable directing group for activation of C-H bonds. The developed procedure results in extremely valuable halogenated N-arylcarbmates that can further be hydrolyzed to halogenated anilines. The obtained reaction conditions showed broad scope and wide functional group tolerance. All the products were formed in good yields with extremely high selectivity.
- Moghaddam, Firouz Matloubi,Tavakoli, Ghazal,Saeednia, Borna,Langer, Peter,Jafari, Behzad
-
p. 3868 - 3876
(2016/05/24)
-
- Aniline carbamates: A versatile and removable motif for palladium-catalyzed directed c-h activation
-
The aniline carbamate is introduced as a new removable directing group for C-H activation. Its versatility and ability as a directing group are demonstrated by its use in the ortho-arylation of a wide variety of aniline derivatives under palladium(II) catalysis, with symmetric diaryliodonium salts as aryl donors. The reaction differs from previously reported arylations in its selectivity and its mechanism, as elucidated by kinetic and isotopic experiments. The directing group can also be easily removed under a variety of conditions.
- Uhlig, Nick,Li, Chao-Jun
-
supporting information
p. 12066 - 12070
(2015/03/31)
-
- GUANIDINE AND AMINE SUBSTITUTED TETRAHYDROISOQUINOLINE COMPOUNDS AS FACTOR XIA INHIBITORS
-
The present invention provides compounds of Formula (I): (Formula (I)) or stereoisomers, pharmaceutically acceptable salts thereof, wherein all of the variables are as defined herein. These compounds are inhibitors of factor XIa and/or plasma kallikrein which may be used as medicaments.
- -
-
Paragraph 00273
(2014/05/07)
-
- 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
-
supporting information
p. 7916 - 7925
(2014/08/18)
-
- (Tosylimino)phenyl-λ3-iodane as a reagent for the synthesis of methyl carbamates via hofmann rearrangement of aromatic and aliphatic carboxamides
-
A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ3-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.
- Yoshimura, Akira,Luedtke, Matthew W.,Zhdankin, Viktor V.
-
experimental part
p. 2087 - 2091
(2012/05/05)
-
- 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)
-
- Synthesis of aryl urea derivatives from aryl amines and aryl isocyanates
-
The present study describes the synthesis of novel diaryl urea derivatives derived from aryl amine and aryl isocyanates. The synthesized compounds are analogs of sorafenib [4-[4-[[[4-chloro-3-(trifluoromethyl)phenyl]amino]carbonyl] amino]phenoxy]-N-methylpyridine-2- carboxamide] having potential antiproliferative activity.
- Usharani,Bhujanga Rao,Reddy,Dubey
-
scheme or table
p. 1802 - 1806
(2011/12/22)
-
- TBCA mediated microwave-assisted Hofmann rearrangement
-
A protocol for the microwave-assisted Hofmann rearrangement mediated by TBCA/KOH/MeOH was developed. Under these conditions high yields and short reaction times were observed for aromatic benzamides.
- Miranda, Leandro S.M.,Da Silva, Thayane Rabello,Crespo, Lívia Tenório,Esteves, Pierre Moth,De Matos, Louise F.,Diederichs, Carla C.,De Souza, Rodrigo Octávio Mendona Alves
-
supporting information; experimental part
p. 1639 - 1640
(2011/04/26)
-
- Gold-catalyzed phosgene-free synthesis of polyurethane precursors
-
(Figure Presented) Golden catalyst: In a two-step one-pot catalytic process gold nanoparticles supported on CeO2 are able to convert nitroaromatics into aromatic carbamates, thereby providing an alternative phosgene-free route towards aromatic polyurethanes (see figure).
- Juarez, Raquel,Concepcion, Patricia,Corma, Avelino,Fornes, Vicente,Garcia, Hermenegildo
-
supporting information; scheme or table
p. 1286 - 1290
(2010/05/18)
-
- Direct fixation of [11C]-CO2 by amines: Formation of [11C-carbonyl]-methylcarbamates
-
[11C-Carbonyl]-methylcarbamates can be synthesised directly from [11C]-CO2 and primary or secondary amines in a one-pot, two-step reaction. The use of either diazabicyclo[5.4.0]undec-7-ene (DBU) or 2-tert-butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2-diazaphosphorine (BEMP) enables efficient trapping of [11C]-CO2 in small volumes of DMF as [11C]-carbamate salts. Subsequent reaction with a variety of methylating agents rapidly generates the desired [ 11C-carbonyl]-methylcarbamates in high radiochemical yields. The usefulness of the method is illustrated by the efficient radiosynthesis of a kappa opioid receptor imaging radiotracer, useful in positron emission tomography (PET).
- Wilson, Alan A.,Garcia, Armando,Houle, Sylvain,Vasdev, Neil
-
experimental part
p. 428 - 432
(2010/02/16)
-
- Indium-catalyzed reaction for the synthesis of carbamates and carbonates: selective protection of amino groups
-
We developed a simple, efficient, and selective method for preparing organic carbamates and carbonates using a catalytic amount of indium. A wide range of carbamates and carbonates were synthesized in high yields. The method is also applicable to the selective protection of amino groups under mild conditions.
- Kim, Joong-Gon,Jang, Doo Ok
-
experimental part
p. 2688 - 2692
(2009/08/09)
-
- Hindered ureas as masked isocyanates: Facile carbamoylation of nucleophiles under neutral conditions
-
Bigger is better: Sterically hindered dialkyl ureas undergo nucleophilic substitution at dramatically faster rates than their less hindered counterparts (see scheme). Steric decompression upon the formation of an intermediate isocyanate can explain this c
- Hutchby, Marc,Houlden, Chris E.,Gair Ford,Tyler, Simon N. G.,Gagne, Michel R.,Lloyd-Jones, Guy C.,Booker-Milburn, Kevin I.
-
supporting information; experimental part
p. 8721 - 8724
(2010/01/16)
-
- An efficient use of microwave-superoxide combination for the synthesis of organic carbamates and dithiocarbamates
-
The present report demonstrates an efficient use of microwave- tetraethylammonium superoxide combination under non-aqueous conditions to bring about a mild and safe carbamation/thiocarbamation of amines, using carbon dioxide/carbon disulfide and methyl iodide.
- Singh, Satish Kumar,Verma, Manjusha,Singh, Krishna Nand
-
experimental part
p. 1545 - 1548
(2009/04/07)
-
- Mild and convenient synthesis of organic carbamates from amines and carbon dioxide using tetraethylammonium superoxide
-
A safe and simple method of preparing organic carbamates has been achieved from amines and carbon dioxide using tetraethylammonium superoxide generated in situ. Copyright Taylor & Francis Group, LLC.
- Singh, Krishna Nand
-
p. 2651 - 2654
(2008/02/12)
-
- A new and convenient in-situ method of generating phenyl isocyanates from anilines using oxalyl chloride
-
A new and convenient method of generating phenyl isocyanates from anilines using oxalyl chloride is described. Acylation of a variety of substituted aniline hydrochlorides with oxalyl chloride affords the intermediate oxamic chlorides, which smoothly undergo thermal decomposition to the corresponding isocyanates.
- Oh, Lynette M.,Spoors, P. Grant,Goodman, Richard M.
-
p. 4769 - 4771
(2007/10/03)
-
- Carbamate synthesis from amines and dimethyl carbonate under ytterbium triflate catalysis
-
A facile synthesis of carbamates from amines and dimethyl carbonate has been achieved using ytterbium triflate as catalyst.
- Curini, Massimo,Epifano, Francesco,Maltese, Federica,Rosati, Ornelio
-
p. 4895 - 4897
(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)
-
- Selective mono-N-methylation of primary aromatic amines by dimethyl carbonate over faujasite X- and Y-type zeolites
-
The reaction of dimethyl carbonate (DMC) with different primary aromatic amines has been investigated under batch conditions (autoclave) in the presence of Y- and X-type zeolites. Operating at 120-150°C, highly selective mono-N-methylations are observed for anilines even when they are deactivated by either electronic effects or steric hindrance (G-C6H4NH2, G = p-NO2,p-CN, o-CO2CH3 and 2,6-dimethylaniline); typical selectivities for the formation of the corresponding mono-N-methyl derivatives [ArNH(CH3)] are in the range 92-98%, at a substrate conversion of 72-93%. A synergic effect between the reactivity of DMC (acting both as a methylating and as a reversible methoxycarbonylating agent) and the dual acid-base properties of zeolites is considered to be responsible for the unusually high selectivity observed; accordingly, a reaction mechanism is discussed, involving carbamates (ArNHCO2CH3) and N-methyl-carbamates [ArN(CH3)CO2CH3] as intermediates. The reaction is an example of a synthesis with low environmental impact: it couples the use of a non-toxic methylating agent (DMC, in place of the highly toxic methyl halides or dimethyl sulfate) with eco-friendly catalysts (zeolites) in a waste-free process.
- Selva, Maurizio,Bomben, Andrea,Tundo, Pietro
-
p. 1041 - 1045
(2007/10/03)
-
- Reductive carbonylation of aromatic dinitro compounds with a palladium(phenanthroline)2(triflate)2 catalyst and an aromatic carboxylic acid as cocatalyst
-
Reductive carbonylation of aromatic dinitro compounds to afford valuable dicarbamates proceeds at reasonable rates and with high selectivities under the influence of a Pd(phenanthroline)2(triflate)2 catalyst in combination with an aromatic carboxylic acid as cocatalyst.
- Wehman, Petra,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
-
p. 217 - 218
(2007/10/03)
-
- The Phthalimidomethyl Rearrangement
-
The discovery of a new acid-catalysed monodentate N -> C aromatic rearrangement, namely the phthalimidomethyl rearrangement, is reported.In this rearrangement, discovered during the reaction of N-hydroxymethylphthalimide with certain alkyl N-(4-nitrophenyl)carbamates in concentrated sulfuric acid solution, the phthalimidomethyl group migrates from its initial location on the nitrogen atom of the carbamate function to a carbon atom of the nitrophenyl group.Evidence, provided by an appropriate 'crossover' experiment, indicates that the rearrangement is intermolecular.Hindered rotation about the N(carbamoyl)-aryl bond of the N-phthalimidomethyl derivatives of both ethyl and methyl N-(2,4-dinitrophenyl)carbamate is reported.
- Wilshire, John F. K.
-
p. 1817 - 1826
(2007/10/02)
-
- NEW METHOD FOR HOFMANN REARRANGEMENT
-
Treatment of a series of primary aliphatic and aromatic carboxamides (1a-1m) with NBS-Hg(OAc)2-R'OH (A), dibromantin-Hg(OAc)2-R'OH (B), NBS-AgOAc-R'OH (C), or dibromantin-AgOAc-R'OH (D) in DMF under argon provides corresponding carbamates (2a-2m) in nearly quantitative yields.
- Jew, Sang-sup,Park, Hyeung Geun,Park, Hee-Joo,Park, Min-soo,Cho, Youn-sang
-
p. 1559 - 1562
(2007/10/02)
-
- Micellar Catalysis of Organic Reactions. XII. Basic Hydrolysis of Some Alkyl and Aryl N-(4-Nitrophenyl)carbamates
-
The basic hydrolysis of a number of alkyl and aryl N-(4-nitrophenyl)carbamates in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab) are reported.In water the stable product at 26 deg C was N-(4-nitrophenyl)carbamate ion (3).At higher temperatures this carbamate ion slowly decomposed to 4-nitroaniline.In ctab the decarboxylation of the N-(4-nitrophenyl)carbamate ion was strongly catalysed (x 45) and thus the observed final product even at 26 deg C was 4-nitroaniline.Kinetic studies in water end in ctab were consistent with decomposition of the methyl carbamate (1a) by a BAC2 mechanism and the 2,2,2-trifluoroethyl carbamate (1c) by an E1cB mechanism.The extent of ionization of the substrate carbamates to nitranion (4) was enhanced in ctab as was the rate of spontaneous decomposition of the nitranion.This is in contrast to other E1cB reactions reported in the literature, for which the rate of spontaneous decomposition of the carbanion was inhibited by ctab.For compounds reacting by the BAC2 mechanism, the tetrahedral intermediate (2) partitioned in favour of C-OR bond breaking rather than C-N bond breaking observed previously for some N-methyl derivatives.
- Broxton, Trevor J.
-
-