13323-81-4Relevant academic research and scientific papers
Direct reductive amination versus hydrogenation of intermediates - A comparison
Tararov, Vitali I.,Kadyrov, Renat,Riermeier, Thomas H.,Fischer, Christine,Boerner, Armin
, p. 561 - 565 (2004)
The direct reductive amination of acetophenone with benzylamine or piperidine was studied in comparison with the hydrogenation of possible intermediates like a corresponding imine or enamine. No common features in terms of productivity and stereo-control (in the case of chiral catalysts) have been found for both processes. Hence evaluation of efficient, selective and enantioselective catalysts for direct reductive animation appears to be a separate task.
Synthesis of efficient Co and N co-doped carbon catalysts with high surface areas for selective oxidation of ethylbenzene
Li, Yuan,Jie, Shanshan,Li, Kun,Liu, Zhigang
, p. 12677 - 12683 (2018)
In this manuscript, Co and N co-doped carbon catalysts with high surface areas were prepared via the pyrolysis of cobalt nitrate and 1,10-phenanthroline monohydrate, using Mg(OH)2 as a pore former, followed by acid etching. Techniques such as B
Reaction of 1,3-dihalopropene with trialkylmanganate
Kakiya, Hirotada,Inoue, Rie,Shinokubo, Hiroshi,Oshima, Koichiro
, p. 73 - 74 (1998)
A three-component coupling reaction was performed. Treatment of 1,3-dibromopropene or 1,3-dichloropropene with tributylmanganate (n-Bu3MnLi) provided a butylated allylmanganese compound which could be trapped by an electrophile such as benzalde
Model compound studies of the beta-O-4 linkage in lignin: absolute rate expressions for beta-scission of phenoxyl radical from 1-phenyl-2-phenoxyethanol-1-yl radical.
Kandanarachchi, Pramod H,Autrey, Tom,Franz, James A
, p. 7937 - 7945 (2002)
Arrhenius rate expressions were determined for beta-scission of phenoxyl radical from 1-phenyl-2-phenoxyethanol-1-yl, PhC*(OH)CH2OPh (V). Ketyl radical V was competitively trapped by thiophenol to yield PhCH(OH)CH2OPh in competition with beta-scission to yield phenoxyl radical and acetophenone. A basis rate expression for hydrogen atom abstraction by sec-phenethyl alcohol, PhC*(OH)CH3, from thiophenol, log(k(abs)/M(-1) s(-1)) = (8.88 +/- 0.24) - (6.07 +/- 0.34)/theta, theta = 2.303RT, was determined by competing hydrogen atom abstraction with radical self-termination. Self-termination rates for PhC*(OH)CH3 were calculated using the Smoluchowski equation employing experimental diffusion coefficients of the parent alcohol, PhCH(OH)CH3, as a model for the radical. The hydrogen abstraction basis reaction was employed to determine the activation barrier for the beta-scission of phenoxyl from 1-phenyl-2-phenoxyethanol-1-yl (V): log(k beta)/s(-1)) = (12.85 +/- 0.22) - (15.06 +/- 0.38)/theta, k beta (298 K) ca. (64.0 s(-1) in benzene), and log(k beta /s(-1)) = (12.50 +/- 0.18) - (14.46 +/- 0.30)/theta, k beta (298 K) = 78.7 s(-1) in benzene containing 0.8 M 2-propanol. B3LYP/cc-PVTZ electronic structure calculations predict that intramolecular hydrogen bonding between the alpha-OH and the -OPh leaving group of ketyl radical (V) stabilizes both ground- and transition-state structures. The computed activation barrier, 14.9 kcal/mol, is in good agreement with the experimental activation barrier.
Racemization of secondary alcohols catalyzed by cyclopentadienyl-ruthenium complexes: Evidence for an alkoxide pathway by fast β-hydride elimination-readdition
Martin-Matute, Belen,Aberg, Jenny B.,Edin, Michaela,Baeckvall, Jan-E.
, p. 6063 - 6072 (2007)
The racemization of sec-alcohols catalyzed by pentaphenylcyclopentadienyl- ruthenium complex 3 a has been investigated. The mechanism involves ruthenium-alkoxide intermediates: reaction of tert-butoxide ruthenium complex 4 with a series of sec-alcohols with different electronic properties gave ruthenium complexes bearing a secondary alkoxide as a ligand. The characterization of these alkoxide complexes by NMR spectroscopy together with a study of the reaction using in situ IR spectroscopy is consistent with a mechanism in which the alkoxide substitution step and the β-hydride elimination step occur without CO dissociation. The alkoxide substitution reaction is proposed to begin with hydrogen bonding of the incoming alcohol to the active ruthenium-alkoxide intermediate. Subsequent alkoxide exchange can occur via two pathways: i) an associative pathway involving a η3-CpRu intermediate; or ii) a dissociative pathway within the solvent cage. Racemization at room temperature of a 1:1 mixture of (S)-1-phenylethanol and (5)-1-phenyl-[D4]-ethanol gave only rac-1-phenylethanol, and rac-1-phenyl-[D4]-ethanol, providing strong support for a mechanism in which the substrate stays coordinated to the metal center throughout the racemization, and does not leave the coordination sphere. Furthermore, racemization of a sec-alcohol bearing a ketone moiety within the same molecule does not result in any reduction of the original ketone, which rules out a mechanism where the intermediate ketone is trapped within the solvent cage. These results are consistent with a mechanism where η3-Ph5C5-ruthenium intermediates are involved. Competitive racemization on nondeuterated and α-deuterated α-phenylethanols was used to determine the kinetic isotope effect k H/kD for the ruthenium-catalyzed racemization. The kinetic isotope effect kH/kD for p-X-C6H 4CH(OH)CH3 was 1.08, 1.27 and 1.45 for X = OMe, H, and CF3, respectively.
Study of the efficiency of amino-functionalized ruthenium and ruthenacycle complexes as racemization catalysts in the dynamic kinetic resolution of 1-phenylethanol
Eckert,Brethon,Li,Sheldon,Arends
, p. 2603 - 2609 (2007)
The ruthenium-amino structural motif in ruthenacycles and aminomethylpyridine ruthenium complexes turned out to be a useful basis for the design of readily accessible and active catalysts for the racemization of alcohols. Inspired by the proven ligand acceleration of 2-aminomethylpyridine (ampy) ligands in ruthenium-catalyzed hydrogen transfer, the readily accessible ampy-based oxazolines 8a and 8b were tested and led to novel and active ruthenium racemization catalysts. The highly active ortho-metalated-ampy Ru complex 7 was demonstrated to be a fast racemization catalyst (100% racemization of 1-phenylethanol at 70°C within 10 min). When used in the dynamic kinetic resolution of 1-phenylethanol towards 1-phenylethyl acetate, the cycloruthenated amine 5 was most active, leading to 86% of the (R)-1-phenylethylacetate with > 99% ee.
Mechanistic studies on ruthenium-catalyzed hydrogen transfer reactions
Laxmi, Y. R. Santosh,Baeckvall, Jan-E.
, p. 611 - 612 (2000)
Ruthenium-catalyzed hydrogen transfer from (S)-α-deuterio-α- phenylethanol [(S)-1] to acetophenone with catalyst 3 occurs with retention of deuterium at the α-carbon of the alcohol product whereas H/D scrambling occurs with catalyst 2.
Selective reduction of aromatic ketones in aqueous medium mediated by Ti(III)/Mn: A revised mechanism
Rosales, Antonio,Mu?oz-Bascón, Juan,Roldan-Molina, Esther,Casta?eda, Mayra A.,Padial, Natalia M.,Gans?uer, Andreas,Rodríguez-García, Ignacio,Oltra, J. Enrique
, p. 7672 - 7676 (2014)
An experimental study on the role played by each of the reagents involved in the selective reduction of aromatic ketones in aqueous medium is reported. In this reaction, the reduction of aromatic ketones is mediated by Cp 2TiCl. Moreover, the presence of Mn in the reaction medium is mandatory. To account for these findings, a substantially revised mechanism is proposed.
Aerobic oxidation of alkanes in the presence of acetaldehyde catalysed by Copper-crown ether
Komiya, Naruyoshi,Naota, Takeshi,Murahashi, Shun-Ichi
, p. 1633 - 1636 (1996)
Copper-crown ether catalysed oxidation of alkanes with molecular oxygen in the presence of acetaldehyde gives the corresponding ketones and alcohols highly efficiently. High turnover numbers have been obtained for the oxidations of cyclohexane using copper(II) chloride and 18-crown-6 as a catalyst.
Tunneling in C-H oxidation reactions by an oxoiron(IV) porphyrin radical cation: Direct measurements of very large H/D kinetic isotope effects
Pan, Zhengzheng,Horner, John H.,Newcomb, Martin
, p. 7776 - 7777 (2008)
Rate constants for oxidations of benzyl alcohol-d0 and -d7 by oxoiron(IV) tetramesitylporphyrin radical cation perchlorate in acetonitrile were measured in single turnover kinetic studies. The kinetic isotope effect (kH/k
