101-99-5Relevant articles and documents
[2+2] and [2+4] type cycloadditions of isocyanates with ynolates
Shindo, Mitsuru,Harada, Akiko,Matsumoto, Kenji,Shishido, Kozo
, p. 39 - 43 (2005)
Ynolates react with isocyanates to give azetidine-2,4-diones via a [2+2] type cycloaddition. The [4+2] type cycloaddition proceeds in the reactions of vinyl isocyanates with ynolates to provide 2-pyridones.
Ultrasound promoted 'one pot' conversion of nitrocompounds to carbamates
Chandrasekhar,Narsihmulu,Jagadeshwar
, p. 771 - 772 (2002)
An efficient ultrasound promoted novel direct conversion of nitro compounds to N-(tert-butoxycarbonyl) amines and N-(ethoxycarbonylamines) is achieved using Sn-NH4Cl for the first time.
Chemistry and antioxidant properties of titanium(IV) complexes
Shaikh, Zara,Ashiq, Uzma,Jamal, Rifat Ara,Mahroof-Tahir, Mohammad,Shamshad, Bushra,Sultan, Sadaf
, p. 665 - 671 (2015)
Abstract The synthesis of titanium(IV) complexes with biologically active hydrazide ligands has been carried out. The complexes were characterized by spectroscopic methods (IR, 1H NMR and 13C NMR), elemental analysis and conductivity studies. These studies suggest bidentate coordination of the ligands through carbonyl oxygen and primary amine nitrogen, resulting in octahedral geometries. Hydrazides with pyridyl substituents displayed 1:2 metal-to-ligand ratio, and hydrazides with imino substituents exhibited 1:3 metal-to-ligand ratio resulting in an outer sphere complex. The remaining complexes displayed inner sphere coordination with 1:1 metal-to-ligand ratio. These complexes exhibit varying degrees of radical scavenging properties against DPPH, superoxide and nitric oxide free radicals. The free ligands showed inhibition against DPPH but were inactive against superoxide and nitric oxide free radicals. The structure-activity relationships of the complexes are discussed.
Kinetics and Mechanism of the Reaction between Phenyl Isocyanate and Alcohols in Benzene Medium
Sivakamasundari, S.,Ganesan, R.
, p. 720 - 722 (1984)
-
-
Bellus,Schaffner
, p. 221 (1968)
-
Selenium-catalyzed oxidative carbonylation of aniline and alcohols to n-phenylcarbamates
Zhang, Xiaopeng,Jing, Huanzhi,Zhang, Guisheng
, p. 1614 - 1624 (2010)
A facile one-pot, phosgene-free synthesis of N-phenylcarbamates is demonstrated. Catalyzed by selenium, oxidative carbonylation of aniline with alcohols in the presence of carbon monoxide and oxygen affords the corresponding N-phenylcarbamates, mostly in fair to good yields. Selenium can be easily recovered because of its phase-transfer catalysis function. Copyright
Cs2CO3 or CaO as promoters of ethyl N-{[(4-methylphenyl)sulphonyl]oxy}carbamate in amination reactions
Barani, Marco,Fioravanti, Stefania,Pellacani, Lucio,Tardella, Paolo A.
, p. 11235 - 11238 (1994)
Replacing triethylamine by heterogeneous inorganic bases makes it possible to aminate benzene or other nitrene acceptors, using the title reagent, previously reported to be scarcely reactive. Products of C-H insertion and/or those coming from intermediate aziridines are also obtained.
Application of Pd(II) Complexes with Pyridines as Catalysts for the Reduction of Aromatic Nitro Compounds by CO/H2O
Krogul, Agnieszka,Litwinienko, Grzegorz
, p. 2017 - 2021 (2015)
Many efforts have been undertaken to minimize the cost of large-scale conversion of aromatic nitro compounds to amines. Toward this end, application of CO/H2O as a reducing agent instead of molecular hydrogen seems to be a promising method, and the process can be catalyzed by Pd(II) complexes. In this work, the catalytic activity of square planar complexes of general structure PdCl2(XnPy)2 (where XnPy = pyridine derivative) was studied. Particular attention was paid to the effects of substituents both in the aromatic ring of XnPy (ligand) and the nitro compound to be reduced (YC6H4NO2). Incorporation of electron-withdrawing Y in the aromatic ring of YC6H4NO2 increases the conversion, indicating that the kinetics of this process is similar to that for the carbonylation of nitrobeznene by CO in the absence of water (described in J. Mol. Catal. A: Chem. 2011, 337, 9-16). Surprisingly, the incorporation of electron-withdrawing substituents into the aromatic ring of the XnPy ligand also increases the conversion of YC6H4NO2 (regardless of the structure of the YC6H4NO2 substrate).
Photoinduced Alcoholysis of the Trichloroacetyl Group
Izawa, Yasuji,Tomioka, Hideo,Natsume, Masashi,Beppu, Shinji,Tsujii, Hideo
, p. 4835 - 4838 (1980)
Irradiation of α,α,α-trichloroacetophenone (1a) in methanol afforded alcoholysis products methyl benzoate (2; X=H, R=Me) and methyl benzoylformate (3; X=H, R=Me) along with dichloroacetophenone.Formation of 2 was greatly favored in the presence of oxygen, whereas that of 3 was favored by the sensitization.Quenching studies showed that both alcoholysis products are derived from different excited triplet states.Reaction mechanisms involving the exciplex between 1 and oxygen are discussed.
Studies on diazepines. VI. Photolysis of 1H-1,2-diazepine and azepine epidioxides
Tsuchiya,Arai,Hasegawa,Igeta
, p. 2205 - 2208 (1978)
-
Copper-Catalyzed Coupling of Amines with Carbazates: An Approach to Carbamates
Wang, Song-Ning,Zhang, Guo-Yu,Shoberu, Adedamola,Zou, Jian-Ping
, p. 9067 - 9075 (2021)
A new approach for the preparation of carbamatesviathe copper-catalyzed cross-coupling reaction of amines with alkoxycarbonyl radicals generated from carbazates is described. This environmentally friendly protocol takes place under mild conditions and is compatible with a wide range of amines, including aromatic/aliphatic and primary/secondary substrates.
Chemical library purification strategies based on principles of complementary molecular reactivity and molecular recognition
Flynn, Daniel L.,Crich, Joyce Z.,Devraj, Rajesh V.,Hockerman, Susan L.,Parlow, John J.,South, Michael S.,Woodard, Scott
, p. 4874 - 4881 (1997)
A new methodology for solution-phase chemical library synthesis and purification is described. This approach applies fundamental properties of complementary molecular reactivity and recognition (CMR/R) as the basis for a general purification strategy. Specifically, parallel solution-phase reactions are purified by resins containing molecular recognition or molecular reactivity functionalities complementary to those of solution- phase reactants, reagents, and byproducts. When used in sequential or simultaneous combinations, various CMR/R resins remove excess reactants, reagents, and byproducts from solution-phase reaction products, which are isolated in purified form by filtration. Where reactions involve the need to remove byproducts or reagents that do not inherently contain sequestrable functionality, sequestration can be effected by the design and use of tagged reactants or reagents containing artificially-imparted molecular recognition functionality. An extension of this methodology utilizes CMR/R resins as the 'quench phase' instead of a liquid-phase workup commonly used in other library purification strategies. Hence, the essential features of complementary molecular reactivity or molecular recognition required for reaction workup are expressed on resins. The CMR/R library purification strategy is general and highly amenable to automation. Examples are illustrated with amine acylations, the Moffatt oxidation, and the reaction of organometallics with carbonyl compounds.
Activation of weak nucleophiles: Polyfluorocarbamates from polyfluoroalcohols via a fast radical reaction
Soto, Marc,Comalrena, Helena,Balduzzi, Ursula,Guirado, Gonzalo,Lloveras, Vega,Vidal-Gancedo, José,Sebastián, Rosa María,Marquet, Jordi
, p. 6310 - 6313 (2013)
A new fast radical mechanism has been observed for the reaction of polyfluorinated alcohols and phenylisocyanate, very sensitive to the change of solvents and the concentration of reactants. The acidity of polyfluoroalcohols seems to be responsible for the observed new reactivity and evidences from kinetic studies, electron paramagnetic resonance, cyclic voltammetry, and photostimulation suggest that polyfluoroalkoxy radical is the key intermediate in the chain. To the best of our knowledge, it is the first time that a radical mechanism is described for the preparation of carbamates.
A Novel Catalytic Synthesis of Carbamates by the Oxidative Alkoxycarbonylation of Amines in the Presence of Platinum Group Metal and Alkali Metal Halide or Onium Halide
Fukuoka, Shinsuke,Chono, Masazumi,Kohno, Masashi
, p. 1458 - 1460 (1984)
Carbamates are prepared in good yields from amines, alcohols, CO, and oxygen in the presence of a novel catalyst system comprising platinum group metal and iodide.
Photo oxygenation of 1H 1,2 diazepine and azepine derivatives: formation and some reactions of their epidioxides
Tsuchiya,Arai,Hasegawa,Igeta
, p. 2749 - 2753 (1977)
-
CARBONYLATION OF NITROSOBENZENES TO CARBAMATE ESTERS CATALYZED BY PALLADIUM AND CUPRIC ACETATES UNDER AMBIENT CONDITIONS
Alper, Howard,Vasapollo, Giuseppe
, p. 6411 - 6412 (1987)
Palladium acetate and cupric acetate are effective catalysts for the reaction of nitrosobenzenes with carbon monoxide and alcohol at room temperature and one atmosphere.
Efficient synthesis of methyl carbamate via Hofmann rearrangement in the presence of TsNBr2
Borah, Arun Jyoti,Phukan, Prodeep
, p. 3035 - 3037 (2012)
An efficient method has been developed for the synthesis of carbamates from the corresponding amides via the Hofmann rearrangement using N,N-dibromo-p-toluenesulfonamide (TsNBr2) in the presence of DBU in methanol. The reaction goes into completion in 10-20 min at 65 °C to produce the corresponding carbamate in excellent yield.
PLATINUM COMPLEX CATALYZED REDUCTIVE N-CARBONYLATION OF NITROARENES TO THE CARBAMATES.
Watanabe,Tsuji,Takeuchi,Suzuki
, p. 3343 - 3348 (1983)
The platinum catalyst combined with triphenylphosphine, tin(IV) chloride, and triethylamine showed high activity for the reductive N-carbonylation of nitroarene in ethanol at 180 degree C under carbon monoxide of 60 kg cm** minus **2. From nitrobenzene, ethyl phenylcarbamate was obtained in 83% yield. Iron(III) chloride, aluminum chloride and titanium(IV) chloride could be used as Lewis acids in place of tin(IV) chloride. Various nitroarenes were transformed into corresponding carbamate in moderate to excellent yields with the platinum catalyst.
A novel PdCl2/ZrO2-SO42- catalyst for synthesis of carbamates by oxidative carbonylation of amines
Shi, Feng,Deng, Youquan,SiMa, Tianlong,Yang, Hongzhou
, p. 525 - 528 (2001)
At 170°C and ca. 4.0 MPa, oxidative carbonylation of aromatic amines to synthesize corresponding carbamates over a novel PdCl2/ZrO2-SO42- catalyst could proceed with high conversion and selectivity.
Selective Ruthenium Carbonyl Catalysed Reductive Carbonylation of Aromatic Nitro Compounds to Carbamates
Cenini, Sergio,Pizzotti, Maddalena,Crotti, Corrado,Porta, Francesca,Monica, Girolamo La
, p. 1286 - 1287 (1984)
Ru3(CO)12 and Ru(CO)3(PPh3)2 catalyse the reductive carbonylation of aromatic nitro compounds to the corresponding carbamates with high selectivity in the presence of NEt4+Cl- as co-catalyst.
THE CATALYTIC CARBONYLATION AT ATMOSPHERIC PRESSURE OF PHENYL AZIDE TO PhNCO, PhNHCONHPh AND PhNHCOOEt
Monica, Girolamo La,Cenini, Sergio
, p. C35 - C37 (1981)
The catalytic activities of rhodium(I) complexes in the carbonylation of phenyl azide at atmospheric pressure, leading to the corresponding isocyanate have been studied. Cl and RhCl(CO)(PPh3)2 are the most active catalysts, and maintain their high activity even in the presence of aniline (which gives diphenylurea) or ethanol (which gives carbamate).
Cyanomethyl anion/carbon dioxide system: An electrogenerated carboxylating reagent. Synthesis of carbamates under mild and safe conditions
Feroci, Marta,Casadei, Maria Antonietta,Orsini, Monica,Palombi, Laura,Inesi, Achille
, p. 1548 - 1551 (2003)
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).
The Palladium catalysed Carbonylation of Nitrobenzene into Phenyl Isocyanate: A Metallacyclic Intermediate
Leconte, P.,Metz, F.,Mortreux, A.,Osborn, J. A.,Paul, F.,et al.
, p. 1616 - 1617 (1990)
A metallacyclic complex has been isolated from the reaction of PhNO2 with CO using the Palladium(II)-o-phenanthroline system known to produce phenyl isocyanate or carbamates catalytically; reactions of this metallacycle have been studied and its role in the catalytic reaction discussed.
Preparation of a novel bromine complex and its application in organic synthesis
Nishio, Yuya,Yubata, Kotaro,Wakai, Yutaro,Notsu, Kotaro,Yamamoto, Katsumi,Fujiwara, Hideki,Matsubara, Hiroshi
, p. 1398 - 1405 (2019)
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.
Transformation of a spirobarbituric acid via aminobarbituric acid-hydantoin rearrangement
Ambrozak, Agnieszka,Guetschow, Michael
, p. 807 - 811 (2006)
A successful application of the aminobarbituric acid-hydantoin rearrangement to produce a bicyclic carbamoylhydantoin from an intermediate spirobarbituric acid is reported. 7a-Phenylcarbamoyl-tetrahydro-1H-pyrrolo[1,2- c]imidazole-1,3(2H)-dione (8) was obtained in a one-pot multistep reaction of 1-acetyl-2,2-bis(ethoxycarbonyl)pyrrolidine (5) and phenylurea in the presence of sodium ethoxide. Under less severe conditions, 5 and phenylurea were reacted to afford 1-acetyl-7-phenyl-triaza[4,5]decane-6,8,10-trione (6). The structural elucidation of the bicyclic hydantoin 8 and the spirobarbituric acid 6 was based on relevant nmr signals in accordance with those of reference compounds, i.e. monocyclic hydantoins 4a,b and acetamidobarbituric acids 2a-c. The latter compounds were newly prepared from diethyl acetamidomalonates 1 and phenylurea.
AgF-Mediated Electrophilic Amination of Alkoxyarylsilanes with Azodicarboxylates
Deng, Shijun,Li, Dong,Shimokawa, Jun,Yorimitsu, Hideki,Zhang, Qian
, (2022/01/31)
A facile and efficient AgF-mediated electrophilic amination of alkoxyarylsilanes with azodicarboxylates was developed. The reaction proceeds in green solvent under simple and mild conditions to generate the corresponding aryl hydrazines. AgF acts both as a stoichiometric fluoride source and a reagent for transmetalation to the arylsilver intermediate that eventually reacts with azodicarboxylates to provide aryl hydrazines.
N-Aryl and N-Alkyl Carbamates from 1 Atmosphere of CO2
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)
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.
