- N-Substituted carbamate synthesis using urea as carbonyl source over TiO2-Cr2O3/SiO2 catalyst
-
The use of urea as an active form of carbon dioxide is a feasible way to substitute phosgene in the chemical industry. This paper reports an effective route for the synthesis of N-substituted carbamates from amines, urea and alcohols. Under the optimized reaction conditions, several important N-substituted carbamates were successfully synthesized in 95-98% yields over a TiO2-Cr2O3/SiO2 catalyst. The catalyst could be reused for several runs without deactivation. The catalysts were characterized by BET, XPS, XRD, and TPD, which suggested that the strength and amount of the acidic and basic sites might be the major reason for the high catalytic activity of TiO2-Cr2O3/SiO2.
- Wang, Peixue,Ma, Yubo,Liu, Shimin,Zhou, Feng,Yang, Benqun,Deng, Youquan
-
p. 3964 - 3971
(2015/07/15)
-
- Copper(II)-catalysed oxidative carbonylation of aminols and amines in water: A direct access to oxazolidinones, ureas and carbamates
-
Copper(II) chloride catalyses the oxidative carbonylation of aminols, amine and alcohols to give 2-oxazolidinones, ureas and carbamates. Reaction proceeds smoothly in water under homogeneous conditions (Ptot = 4 MPa; PO2 = 0.6 MPa, PCO), at 100°C in relatively short reaction times (4 h) and without using bases or any other additives. This methodology represents an economic and environmentally benign non-phosgene alternative for the preparation of these three important N-containing carbonyl compounds.
- Casiello, Michele,Iannone, Francesco,Cotugno, Pietro,Monopoli, Antonio,Cioffi, Nicola,Ciminale, Francesco,Trzeciak, Anna M.,Nacci, Angelo
-
-
- Structure-activity relationships of a small-molecule inhibitor of the PDZ domain of PICK1
-
Recently, we described the first small-molecule inhibitor, (E)-ethyl 2-cyano-3-(3,4-dichlorophenyl)acryloylcarbamate (1), of the PDZ domain of protein interacting with Cα-kinase 1 (PICK1), a potential drug target against brain ischemia, pain and cocaine addiction. Herein, we explore structure-activity relationships of 1 by introducing subtle modifications of the acryloylcarbamate scaffold and variations of the substituents on this scaffold. The configuration around the double bond of 1 and analogues was settled by a combination of X-ray crystallography, NMR and density functional theory calculations. Thereby, docking studies were used to correlate biological affinities with structural considerations for ligand-protein interactions. The most potent analogue obtained in this study showed an improvement in affinity compared to 1 and is currently a lead in further studies of PICK1 inhibition.
- Bach, Anders,Stuhr-Hansen, Nicolai,Thorsen, Thor S.,Bork, Nicolai,Moreira, Irina S.,Frydenvang, Karla,Padrah, Shahrokh,Christensen, S. Brogger,Madsen, Kenneth L.,Weinstein, Harel,Gether, Ulrik,Stromgaard, Kristian
-
supporting information; experimental part
p. 4281 - 4288
(2010/11/05)
-
- Cyclic guanidine organic catalysts: What is magic about triazabicyclodecene?
-
(Chemical Equation Presented) The bicyclic guanidine 1,5,7- triazabicyclo[4.4.0]dec-5-ene (TBD) is an effective organocatalyst for the formation of amides from esters and primary amines. Mechanistic and kinetic investigations support a nucleophilic mechanism where TBD reacts reversibly with esters to generate an acyl-TBD intermediate that acylates amines to generate the amides. Comparative investigations of the analogous bicyclic guanidine 1,4,6-triazabicyclo[3.3.0]oct-4-ene (TBO) reveal it to be a much less active acylation catalyst than TBD. Theoretical and mechanistic studies imply that the higher reactivity of TBD is a consequence of both its higher basicity and nucleophilicity than TBO as well as the high reactivity of the acyl-TBD intermediate, which is sterically prevented from adopting a planar amide structure.
- Kiesewetter, Matthew K.,Scholten, Marc D.,Kirn, Nicole,Weber, Ryan L.,Hedrick, James L.,Waymouth, Robert M.
-
supporting information; experimental part
p. 9490 - 9496
(2010/03/24)
-
- Catalytic activity of MCM-41-TBD in the selective preparation of carbamates and unsymmetrical alkyl carbonates from diethyl carbonate
-
The synthesis of carbamates 3 and unsymmetrical alkyl carbonates 5 by reaction of diethyl carbonate with aliphatic amines or alcohols has been realized by using as heterogeneous catalyst a hybrid organic-inorganic material prepared by anchoring TBD to MCM-41 silica. Products are obtained in high yield and very good selectivity and the solid catalyst can be recovered simply by filtration and reused for different cycles without apparent lowering of activity. A supported N -carbethoxyguanidinium active intermediate is proposed, and some spectroscopic data are shown to support the mechanistic hypothesis.
- Carloni, Silvia,De Vos, Dirk E.,Jacobs, Pierre A.,Maggi, Raimondo,Sartori, Giovanni,Sartorio, Raffaella
-
p. 199 - 204
(2007/10/03)
-
- A novel PdCl2/ZrO2-SO42- catalyst for synthesis of carbamates by oxidative carbonylation of amines
-
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.
- Shi, Feng,Deng, Youquan,SiMa, Tianlong,Yang, Hongzhou
-
p. 525 - 528
(2007/10/03)
-
- 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)
-
- Processes for producing carbamates and isocyanates
-
Processes for producing carbamates comprise contacting a first reactant selected from primary amine components, secondary amine components, urea components and mixtures thereof; carbon monoxide; at least one organic hydroxyl component and at least one oxygen-containing oxidizing agent in the presence of a catalyst composition comprising at least one metal macrocyclic complex, preferably in the further presence of a halogen component.
- -
-
-
- Preparation of urethanes by oxidative carbonylation of amines using copper carboxylates as oxidants
-
A process for preparing urethanes by reacting a primary or secondary amine with carbon monoxide, an alcohol, a catalytic quantity of a compound or complex of palladium, platinum or rhodium and a stoichiometric quantity of a copper(II) salt of a monocarboxylic acid. When the amine is aromatic, the process is conducted in the presence of a selected Lewis base promoter and a compound or complex of palladium.
- -
-
-
- Chemical Ionization Mass Spectra of Urethanes
-
Chemical ionization mass spectra using methane as the reagent gas are reported for 33 urethanes of general structure RNHCO2C2H5 nH2n+1 (n=1-8), CH2CH=CH2, cyclo-C6H11, Ph, PhCH2, PhCH2CH2, and Ph(CH3)CH> and R2NCO2C2H5 nH2n+1 (n=1-4)>.Abundant MH+ ions are present in all the spectra, accompanied by satellite peaks corresponding to + and +.Four classes of fragment ions are of general importance in the spectra.Two of these, + and +, are associated with the CO2C2H5 group.The other two, corresponding to alkane and alkene elimination from MH+, arise from the RNH or R2N function.The mechanisms whereby these fragment ions are formed are discussed and their analytical utility is illustrated by reference to the spectra of the four isomeric C4H9NHCO2C2H5 and the eight isomeric C5H11NHCO2C2H5 compounds.The results of 2H-labelling studies are presented and a comparison is made between the methane and ammonia chemical ionisation spectra of selected urethanes.
- Wright, Andrew D.,Bowen, Richard D.,Jennings, Keith R.
-
p. 1521 - 1528
(2007/10/02)
-
- Low-energy, Low-temperature Mass Spectra. 10-Urethanes
-
The 12.1 eV, 75 deg C electron impact mass spectra of 24 urethanes, RNHCO2C2H5 nH2n+1 (n = 1-8), CH2=CHCH2, Ph, PhCH2 and PhCH2CH2>, and seven symmetrically disubstituted urethanes R2NCO2C2H5 (R = CnH2n+1 (n = 1-4) are reported and discussed.All 31 spectra show appreciable molecular ion peaks.For n-CnH2n+1NHCO2C2H5, M+. usually is the most abundant ion in the spectrum.A peak at m/z 102 of comparable intensity also is present; this corresponds to formal cleavage of the bond connecting the α- and β-carbon atoms in the N-alkyl group, though it is unlikely that the daughter ion has the structure (1+).In the RNHCO2C2H5 series, branching at the α-carbon atom enhances the relative abundance of the ion arising by notional α-cleavage at the expense of that of M+..Formal cleavage of the bond between β- and γ-carbon atoms occurs to some extent for +. ions; this reaction provides information on the degree of branching at the β-carbon, especially if metastable molecular ions are considered.The higher n-CnH2n+1NHCO2C2H5 (n = 5-8) urethanes exhibit two other significant ions in their mass spectra.First, there is a peak at (1+).Secondly, a peak is present at m/z 90; the most plausible structure for this ion is (1+), arising by double hydrogen transfer from the alkyl group and expulsion of a nH2n-1>. radical.Ions originating from secondary decomposition of the primary ionic species are generally of only very low abundance in these spectra.
- Bowen, Richard D.,Maccoll, Allan
-
p. 113 - 122
(2007/10/02)
-
- Ion-Dipole Complexes in the Unimolecular Reactions of Isolated Organic Ions. Effect of N-Methylation on Olefin and Amine Loss from Protonated Aliphatic Amines
-
The slow unimolecular fragmentation reactions os 18 gaseous protonated aliphatic amines of general formula R1NH(1+)R2R3 (R1=Prn, Pri, Bun, Bui, Bus, or But; R2,R3=H,CH3) are reported and discussed.Two decomposition routes are observed for a metastable ions R1NH(1+)R2R3.The first involves elimination of a neutral amine, R2R3NH, and formation of a carbocation, R1(1+), via a mechanism involving an incipient cation bound to the developing amine by an ion-dipole attraction.Rearrangement of the cation, to give thermodynamically more stable isomers, is feasible in these ion-dipole complexes.Further reorganization of the complexes leads to a species in which an incipient olefin 1-H> and an amine 2R3NH> are co-ordinated to a common proton.Dissociation of these proton-bound complexes, with retention of the proton by the developing amine, results in olefin loss, which is the secondreaction undergone by metastable ions R1NH(1+)R2R3.The relative abundance of amine expulsion is greater for protonated amines containing a primary alkyl group, R1, than is the case for isomeric ions containing secondary or tertiary alkyl groups.Progressive methylation of the nitrogen atom decreases the relative abundance of amine loss from R1NH(1+)R2R3, regardless of the nature of the principal alkyl group.These two trends are explained in terms of the energetics of the intermediates and products involved in the decomposition of the protonated amines.
- Bowen, Richard D.,Harrison, Alex G.,Reiner, Eric J.
-
p. 1009 - 1014
(2007/10/02)
-
- Production of urethane compounds
-
A process for producing a urethane compound which comprises reacting at least one compound selected from the group consisting of a primary amine, a secondary amine and a urea compound with carbon monoxide and an organic hydroxyl compound in the presence of a catalyst system comprising: (a) at least one member selected from the group consisting of platinum group metals and compounds containing at least one platinum group element; and (b) at least one halogen-containing compound selected from the group consisting of alkali or alkaline earth metal halides, onium halides, compounds capable of forming onium halides in the reaction, oxo acids of halogen atoms and their salts, complex compounds containing halogen ions, organic halides and halogen molecules, in the presence of molecular oxygen and/or an organic nitro compound as an oxidizing agent at a temperature of from about 80° C. to about 300° C. under a pressure of from about 1 Kg/cm2 to about 500 Kg/cm2.
- -
-
-
- Triphenodioxazine acid dyes
-
Triphenodioxazine dyes which, in the free acid form, have the formula: STR1 wherein A is Cl or Br; Y is cyclopentylene, cyclohexylene or (CH2)x where x is 2, 3 or 4; and Z is NRCO2 R1 or STR2 wherein R is H, optionally substituted alkyl or optionally substituted aryl; R1 is optionally substituted alkyl, optionally substituted cycloalkyl or optionally substituted aryl; and R2 is --CH=CH--,--CH=CH--CH2 --,--(CH2)--2-4 or a 1,2-radical of a 5 or 6 membered carbocyclic compound; or, when Y is cyclopentylene or cyclohexylene, Z may also be H or alkyl, alkoxy, aryl, aryloxy, cycloalkyl, cycloalkoxy or amino, all of which may be optionally substituted.
- -
-
-
- 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
-
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.
- Fukuoka, Shinsuke,Chono, Masazumi,Kohno, Masashi
-
p. 1458 - 1460
(2007/10/02)
-
- PYROTHIOCARBONATES I. AMINOLYSIS OF S-(ETHOXYCARBONYL) O-ETHYL DITHIOCARBONATE
-
The reaction of S-(ethoxycarbonyl) O-ethyl dithiocarbonate (1) with equimolar amounts of butylamine, benzylamine, diethylamine and piperidine in ethanol solution at 0 deg C is reported.The mole ratio of O-ethyl thiocarbamate (2) and O-ethyl carbamate (3) formed as main products is larger than unity during all the reaction.Bis(ethoxythiocarbonyl) sulfide (4) and bis(ethoxycarbonyl) sulfide (5) are also produced and their formation is explained in terms of the reaction of 1 with EtOCS2- and EtOCOS-, respectively, which are the leaving groups in the aminolysis of 1.Reactions 4 -> 2 and 5 -> 3 also take place.When 50percent of 1 has been consumed compound 4 is not detected and compound 5 is found at very low concentration, indicating that generation of 4 and 5 occurs mainly after aminolysis of 1.The fact that the ratio of 2 : 3 is larger than unity in this aminolysis step, and that S-methyl O-ethyldithiocarbonate is aminolyzed more readily than S-methyl O-ethylmonothiocarbonate under the same conditions as the aminolysis of 1, suggests that the thiocarbonyl group of 1 is more reactive than the carbonyl group.
- Palominos, Mario A.,Santos, Jose G.,Valderrama, Jaime A.,Vega, Juan C.
-
p. 245 - 252
(2007/10/02)
-
