3282-27-7Relevant academic research and scientific papers
Catalytic hydration of cyanamides with phosphinous acid-based ruthenium(ii) and osmium(ii) complexes: scope and mechanistic insights
álvarez, Daniel,Cadierno, Victorio,Crochet, Pascale,González-Fernández, Rebeca,López, Ramón,Menéndez, M. Isabel
, p. 4084 - 4098 (2020/07/09)
The synthesis of a large variety of ureas R1R2NC(O)NH2 (R1 and R2 = alkyl, aryl or H; 26 examples) was successfully accomplished by hydration of the corresponding cyanamides R1R2NCN using the phosphinous acid-based complexes [MCl2(η6-p-cymene)(PMe2OH)] (M = Ru (1), Os (2)) as catalysts. The reactions proceeded cleanly under mild conditions (40-70 °C), in the absence of any additive, employing low metal loadings (1 molpercent) and water as the sole solvent. In almost all the cases, the osmium complex 2 featured a superior reactivity in comparison to that of its ruthenium counterpart 1. In addition, for both catalysts, the reaction rates observed for the hydration of the cyanamide substrates were remarkably faster than those involving classical aliphatic and aromatic nitriles. Computational studies allowed us to rationalize all these trends. Thus, the calculations indicated that the presence of a nitrogen atom directly linked to the CN bond depopulates electronically the nitrile carbon by inductive effect when coordinated to the metal center, thus favouring the intramolecular nucleophilic attack of the OH group of the phosphinous acid ligand to this carbon. On the other hand, the higher reactivity of Os vs. Ru seems to be related with the lower ring strain on the incipient metallacycle that starts to form in the transition state associated with this key step in the catalytic cycle. Indirect experimental evidence of the generation of the metallacyclic intermediates was obtained by studying the reactivity of [RuCl2(η6-p-cymene)(PMe2OH)] (1) towards dimethylcyanamide in methanol and ethanol. The reactions afforded compounds [RuCl(η6-p-cymene)(PMe2OR)(NCNMe2)][SbF6] (R = Me (5a), Et (5b)), resulting from the alcoholysis of the metallacycle, which could be characterized by single-crystal X-ray diffraction. This journal is
Iron-catalyzed reaction of urea with alcohols and amines: A safe alternative for the synthesis of primary carbamates
Pe?a-López, Miguel,Neumann, Helfried,Beller, Matthias
, p. 2233 - 2238 (2017/07/25)
A general study of the iron-catalyzed reaction of urea with nucleophiles is here presented. The carbamoylation of alcohols allows for the synthesis of N-unsubstituted (primary) carbamates, including present drugs (Felbamate and Meprobamat, without the necessity to apply phosgene and related derivatives. Using amines as nucleophiles gave rise to the respective mono-and disubstituted ureas via selective transamidation reaction. These atom-economical transformations provide a direct and selective access to valuable compounds from cheap and readily available urea using a simple Lewis-acidic iron(Icatalyst.
Hydration of Nitriles to Amides by Thiolate-Bridged Diiron Complexes
Tong, Peng,Yang, Dawei,Li, Yang,Wang, Baomin,Qu, Jingping
, p. 3571 - 3576 (2015/08/06)
A series of nitrile-coordinating complexes [CpFe(μ-SEt)RCN]2[PF6]2 (1, R = alkyl, aryl, vinyl, amine) have been obtained by the reaction of [CpFe(μ-SEt)MeCN]2[PF6]2 (1a) with various nitriles in acetone. Complexes 1 can realize the hydration of a nitrile ligand under ambient conditions. Complexes [CpFe(μ-SEt)2(μ-η1:η1-NH(O)CR)FeCp][PF6] (2) were successfully isolated as intermediates during the hydration process, with 2b and 2e (R = CH2i = CH and Et2N) being characterized by spectrometry and X-ray crystallography. Treatment of 2 with HBF4·Et2O in the presence of nitriles released corresponding amides 3. At the same time, the structural features of the [Fe2S2] scaffold were retained. These results confirmed that the hydration of nitriles was realized by cooperative interaction on diiron centers. (Figure Presented).
Phosphinoureas: Cooperative ligands in rhodium-catalyzed hydroformylation? on the possibility of a ligand-assisted reductive elimination of the aldehyde
Meeuwissen, Jurjen,Sandee, Albertus J.,De Bruin, Bas,Siegler, Maxime A.,Spek, Anthony L.,Reek, Joost N. H.
experimental part, p. 2413 - 2421 (2010/08/04)
We report the synthesis of a novel type of phosphinourea ligand, its coordination chemistry with rhodium, its use in the asymmetric hydroformylation of styrene, and investigations on the hydroformylation reaction mechanism. Complex studies on the 2:1 complex of phosphinourea to [Rh(acac)(CO) 2] showed that a neutral trans-coordinating complex [Rh(HL-κP)(L-κ2O,P)(CO)] was formed. An anionic O,P-chelating ligand has displaced the anionic acac- ligand via an acid-base reaction involving the deprotonation of an acidic urea proton, giving Hacac. A second phosphinourea is coordinated as a neutral monodentate ligand and is linked to the chelating anionic ligand via an intramolecular hydrogen bond. The behavior of these supramolecular complexes in the hydroformylation reaction and the possible cooperative role of the ligands in the catalytic cycle were studied both experimentally and by computational methods. High-pressure NMR spectroscopy revealed that the catalytically active rhodium hydride species further consists of two neutral phosphinourea ligands and is in equilibrium with the neutral species [Rh(HL-κP)(L-κ2O,P)(CO)]. This equilibrium is likely an integrated part of a productive hydroformylation cycle involving a ligand-assisted reductive elimination of the aldehyde. DFT calculations revealed that the ligand-assisted mechanism could well be the preferred lower energetic pathway; however, the orientation of the anionic oxygen donor atom in [Rh(HL-κP)(L-κ2O,P)(CO)] prevented us from finding a direct (nonsolvent assisted) transition state to connect the intermediates. We therefore cannot exclude a mechanism where [Rh(HL-κP)(L-κ2O,P)(CO)] is a dormant species outside the productive hydroformylation cycle, although the intermediate associated with this mechanism is higher in energy. Finally, the synthesis of heteroligated complexes was investigated, consisting of two electronically different phosphinoureas, which sets the stage for combinatorial supramolecular ligand approaches in catalysis. Simply mixing two electronically different phosphinoureas with metal precursor [Rh(acac)(CO)2] resulted in the formation of a heterobidentate ligand. A set of six new phosphinoureas was used to prepare such rhodium complexes in a combinatorial fashion for the asymmetric hydroformylation of styrene, resulting in high conversions and selectivities for the branched product and moderate enantioselectivities.
Aromatic borylation/amidation/oxidation: A rapid route to 5-substituted 3-amidophenols
Shi, Feng,Smith III, Milton R.,Maleczka Jr., Robert E.
, p. 1411 - 1414 (2007/10/03)
5-Substituted 3-amidophenols are prepared by subjecting 3-substituted halobenzenes to an Ir-catalyzed aromatic borylation, followed by a Pd-catalyzed amidation, and finally an oxidation of the boronic ester intermediate. The entire C-H activation borylation/amidation/oxidation sequence can be accomplished without isolation of any intermediate arenes. Usefully, amide partners can include lactams, carbamates, and ureas.
Methods of treating nuclear factor-kappa B mediated diseases and disorders
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, (2008/06/13)
The present invention provides a method of treating a disease or a disorder responsive to inhibition of nuclear factor-κB transcription factors comprising administering to a patient in need thereof a sulfonylaminocarbonyl derivative, or a pharmaceutically acceptable salt thereof. The methods of the present invention are useful for treating, for example, rheumatoid arthritis, osteoarthritis, an autoimmune disease, psoriasis, asthma, a cardiovascular disease, an acute coronary syndrome, congestive heart failure, Alzheimer's disease, multiple sclerosis, cancer, type 2 diabetes, metabolic syndrome X, or inflammatory bowel disease.
Ureas in Organic Synthesis. XI. Reactions of Arylcarbinols with Carbamides in Synthesis of Biologically Active Arylmethylureas
Bakibaev, A. A.
, p. 1433 - 1437 (2007/10/03)
The reaction of arylcarbinols with carbamide in the presence of acids affords the corresponding arylmethylureas.
Process for the preparation of asymmetrically substituted ureas
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, (2008/06/13)
Process for the preparation of asymmetrically substituted ureas by reaction of a gaseous mixture of isocyanic acid and ammonia having a temperature of 260° to 600° C. with a primary or secondary amine.
