19781-62-5Relevant academic research and scientific papers
Trans-Selective and Switchable Arene Hydrogenation of Phenol Derivatives
Bergander, Klaus,Glorius, Frank,Heusler, Arne,Wollenburg, Marco
, p. 11365 - 11370 (2020/11/24)
A trans-selective arene hydrogenation of abundant phenol derivatives catalyzed by a commercially available heterogeneous palladium catalyst is reported. The described method tolerates a variety of functional groups and provides access to a broad scope of trans-configurated cyclohexanols as potential building blocks for life sciences and beyond in a one-step procedure. The transformation is strategically important because arene hydrogenation preferentially delivers the opposite cis-isomers. The diastereoselectivity of the phenol hydrogenation can be switched to the cis-isomers by employing rhodium-based catalysts. Moreover, a protocol for the chemoselective hydrogenation of phenols to cyclohexanones was developed.
Ruthenium Nanoparticles Stabilized in Cross-Linked Dendrimer Matrices: Hydrogenation of Phenols in Aqueous Media
Maximov, Anton,Zolotukhina, Anna,Murzin, Vadim,Karakhanov, Edward,Rosenberg, Edward
, p. 1197 - 1210 (2015/04/14)
Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975h-1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinoneacatechol. The maximum specific activity for resorcinol was a turnover frequency of 243150h-1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity.
Asymmetric microbial reduction of ketones: absolute configuration of trans-4-ethyl-1-(1S-hydroxyethyl)cyclohexanol
Pinedo-Rivilla, Cristina,Cafeu, Mariana Carrara,Casatejada, Josefina Aleu,Araujo, Angela Regina,Collado, Isidro G.
experimental part, p. 2666 - 2672 (2010/05/17)
A set of five fungal species, Botrytis cinerea, Trichoderma viride and Eutypa lata, and the endophytic fungi Colletotrichum crassipes and Xylaria sp., was used in screening for microbial biocatalysts to detect monooxygenase and alcohol dehydrogenase activities (for the stereoselective reduction of carbonyl compounds). 4-Ethylcyclohexanone and acetophenone were biotransformed by the fungal set. The main reaction pathways involved reduction and hydroxylations at several positions including tertiary carbons. B. cinerea was very effective in the bioreduction of both substrates leading to the chiral alcohol (S)-1-phenylethanol in up to 90% enantiomeric excess, and the cis-trans ratio for 4-ethylcyclohexanol was 0:100. trans-4-Ethyl-1-(1S-hydroxyethyl)cyclohexanol, obtained from biotransformation by means of an acyloin-type reaction, is reported here for the first time. The absolute configurations of the compounds trans-4-ethyl-1-(1S-hydroxyethyl)cyclohexanol and 4-(1S- and 4-(1R-hydroxyethyl)cyclohexanone were determined by NMR analysis of the corresponding Mosher's esters.
Raney Ni-Al alloy-mediated reduction of alkylated phenols in water
Tan, Song-Liang,Liu, Guo-Bin,Gao, Xiang,Thiemann, Thies
experimental part, p. 5 - 7 (2009/09/06)
Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a very powerful reducing agent in the hydrogenation of phenol and alkylated phenols to the corresponding cyclohexanol derivatives.
Hydroamination of alkylphenols by nitriles
Tarasevich,Zhavrid,Kozlov
, p. 1154 - 1159 (2007/10/03)
N-(Alkyl(alkylcyclohexyl)amines were synthesized by hydroamination of o-, m-, and p-alkyl-phenols with aliphatic nitriles. The stereochemistry of the secondary amines formed is described.
ENZYMATIC "IN VITRO" REDUCTION OF KETONES. Part 10. Study of 3-Acetylpyridine Adenine Dinucleotide in a Co-enzyme Recycling System Ethanol-Ketone-3-AcPyAD+-HLAD
Lemiere, Guy L.,Jaco, Jan,Merckx, Erik M.,Lepoivre, Josef A.,Alderweireldt, Frank C.
, p. 747 - 752 (2007/10/02)
The NAD+ analogue 3-acetylpyridine adenine dinucleotide (3-AcPyAD+) has been studied in the co-enzyme recycling system ethanol-ketone-3-AcPyAD+-HLAD.All reaction parameters are tested in analogous conditions as for the NAD+-recycling system.The stereospecificity of the new system is investigated for the reduction of 4-, 3- and 2-alkylcyclohexanones.The new recycling system is kinetically and stereochemically very similar to the NAD+ system, but 3.2 times slower.
ENZYMATIC "IN VITRO" REDUCTION OF KETONES. VI.(1) Reduction rates and stereochemistry of the HLAD-catalyzed reduction of 3-alkyl- and 4-alkylcyclohexanones.
Osselaer, T. A. Van,Lemiere, G. L.,Lepoivre, J. A.,Alderweireldt, F. C.
, p. 133 - 150 (2007/10/02)
Reaction rate constants for the catalytic step HLAD-NADH + ketone * HLAD-NAD+ + alcohol in the HLAD-catalyzed reduction of 3-alkyl- and 4-alkylcyclohexanones are determined from initial rate measurements in the coenzyme recycling system ketone-ethanol-NAD+-HLAD.By rate measurements at several temperatures, activation parameters were determined and isokinetic relationships tracked down.Two different isokinetic relationships show that the 3-alkylcyclohexanones pass through an other type of transition state than cyclohexanone and the 4-alkylcyclohexanones, which means that they have a different arrangement on the HLAD-NADH complex.The results are rationalized in view of the most recent principles on nucleophilic additions to carbonyl functions.The resulting model for the HLAD-catalyzed reduction adequately explains the observed rate accelerating and decelerating effects and the stereochemistry of the reduction as well.
