1009-67-2Relevant articles and documents
Gas-phase pyrolytic reaction of 3-phenoxy and 3-phenylsulfanyl-1-propanol derivatives: Kinetic and mechanistic study
Dib,Ibrahim,Al-Awadi,Ibrahim,Al-Awadi
, p. 51 - 58 (2008)
3-Phenoxy-l-propanols 1a-c and 3-phenylsuIfanyl-1-propanols 2a-c containing primary, secondary, and tertiary alcohols were prepared and subjected to gas-phase pyrolysis in a static reaction system. Pyrolysis of 4-phenyl-1-butanol 3, 2-methyl-3-phenyl-1-propanol 4, and 2-methyl-3-phenylpropanoic acid 5 was also studied, and results were compared with those obtained for compounds 1-3. The pyrolytic reactions were homogeneous and followed a first-order rate equation. Analysis of the pyrolysate showed the products to be phenol (from la to 1c), thiophenol (from 2a to 2c), and toluene (from 3 to 5) and carbonyl compounds. The kinetic results and product analysis of each of the nine investigated compounds are rationalized in terms of a plausible transition state for the elimination pathway.
Model Studies on the Enzyme-Regulated Stereodivergent Cascade Passerini Reaction
Brodzka, Anna,Koszelewski, Dominik,Ostaszewski, Ryszard,Samsonowicz-Górski, Jan,Wilk, Monika
, p. 4161 - 4165 (2021)
The synthesis of chiral α-acyloxy carboxamides containing two stereogenic centers continues to be a challenging field of organic chemistry. Herein, we have proposed and proved the feasibility of an enzyme regulated-cascade reaction, which using the same substrates enables the formation of individual stereoisomers of α-acyloxy carboxamides with up to 99 % ee. The access to the individual stereoisomeric products has been achieved by a combination of the enzymatic kinetic resolution of racemic vinyl esters, subsequent Passerini reaction, and enzymatic kinetic resolution of formed α-acyloxy carboxamides. The presented studies are promising in exploratory proof-of-concept of enzyme-controlled stereodivergent cascade to form an important class of chiral compounds for medicinal chemistry.
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Reinheckel,H.,Tauber,G.
, p. 1944 - 1953 (1967)
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New types of o-carborane-based chiral phosphinooxazoline (Cab-PHOX) ligand systems: Synthesis and characterization of chiral Cab-PHOX ligands and their application to asymmetric hydrogenation
Lee, Jong-Dae,Thanh, Thien Co,Kim, Tae-Jeong,Sang, Ook Kang
, p. 771 - 774 (2009)
o-Carborane-based chiral phosphinooxazoline (Cab-PHOX) ligands were synthesized for the first time and applied to the iridium- and rhodium-catalyzed hydrogenation of unfunctionalized and functionalized olefins with an enantioselectivity of up to 98% and 96%, respectively. The modularity of the Cab-PHOX ligands is highlighted by the facile preparation of a variety of sterically and electronically different ligands. Georg Thieme Verlag Stuttgart.
Enantioselective Hydrogenation of α-Methylcinnamic Acid over Pd/Al2O3: A Kinetic Study of Solvent, Temperature and Pressure Effects
Sun, Xiaojing,Monnier, John R.,Williams, Christopher T.
, p. 881 - 886 (2013)
The enantioselective hydrogenation of α-methylcinnamic acid (MCA) over cinchonidine modified 5 wt% Pd/Al2O3 was studied in a liquid batch reactor. Both the reaction activity and enantioselectivity towards the (R) product are strongly solvent dependent. The reaction is zero order in hydrogen pressure and first order in MCA. The presence of cinchonidine does not affect the reaction order with respect to either acid or H2 pressure, but has a significant inhibiting effect on the reaction rate. The catalyst exhibits stable activity during the reaction with no sign of deactivation. Graphical Abstract: [Figure not available: see fulltext.]
COPPER-CATALYZED REACTION OF GRIGNARD REAGENTS WITH β-PROPIOLACTONES: A CONVENIENT METHOD FOR THE SYNTHESIS OF Β-SUBSTITUTED PROPIONIC ACIDS
Sato, Toshio,Kawara, Tatsuo,Kawashima, Masatoshi,Fujisawa, Tamotsu
, p. 571 - 574 (1980)
Grignard reagents react with β-propiolactones in the presence of a copper(I) catalyst to give β-substituted propionic acids in high yields.
Acceleration of enantioselective hydrogenation of olefins over Pd/C by cinchonidine as a chiral modifier. Comparison with cinchonine, pseudoenantiomer
Sugimura, Takashi,Ogawa, Hiroyuki
, p. 232 - 233 (2010)
The performance of cinchonidine (CD) and cinchonine (CN) as chiral modifiers in enantioselective hydrogenation over Pd/C were compared in different concentrations. The catalytic hydrogenation with CD always occurred in better ee and at faster rate than that with CN. The difference is not attributable to the adsorption properties of the modifiers, but to the intrinsic enantio differentiation that accompanies the reaction acceleration.
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Kenyon,Ross
, p. 3407,3409 (1951)
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Magnetic nanoparticles entrapped in siliceous mesocellular foam: A new catalyst support
Lee, Su Seong,Riduan, Siti Nurhanna,Erathodiyil, Nandanan,Lim, Jaehong,Cheong, Jian Liang,Cha, Junhoe,Han, Yu,Ying, Jackie Y.
, p. 7394 - 7403 (2012)
γ-Fe2O3 nanoparticles were formed inside the cage-like pores of mesocellular foam (MCF). These magnetic nanoparticles showed a uniform size distribution that could be easily controlled by the MCF pore size, as well as by the hydrocarbon chain length used for MCF surface modification. Throughout the entrapment process, the pore structure and surface area of the MCF remained intact. The resulting magnetic MCF facilitated the immobilization of biocatalysts, homogeneous catalysts, and nanoclusters. Moreover, the MCF allowed for facile catalyst recovery by using a simple magnet. The supported catalysts exhibited excellent catalytic efficiencies that were comparable to their homogeneous counterparts. Copyright
Aguiar et al.
, p. 1545,1547 (1976)
Efficient cluster-based catalysts for asymmetric hydrogenation of α-unsaturated carboxylic acids
Moberg, Viktor,Duquesne, Robin,Roehrs, Oliver,Nachtigall, Jonny,Nordlander, Ebbe,Contaldi, Simone,Monari, Magda,Damoense, Llewellyn,Green, Michael,Hutton, Alan T.,Santelia, Daniela,Haukka, Matti
, p. 12458 - 12478,21 (2012)
The new clusters [H4Ru4(CO)10(μ-1,2-P- P)], [H4Ru4(CO)10(1,1-P-P)] and [H 4Ru4(CO)11(P-P)] (P-P=chiral diphosphine of the ferrocene-based Josiphos or Walphos ligand families) have been synthesised and characterised. The crystal and molecular structures of eleven clusters reveal that the coordination modes of the diphosphine in the [H4Ru 4(CO)10(μ-1,2-P-P)] clusters are different for the Josiphos and the Walphos ligands. The Josiphos ligands bridge a metal-metal bond of the ruthenium tetrahedron in the "conventional" manner, that is, with both phosphine moieties coordinated in equatorial positions relative to a triangular face of the tetrahedron, whereas the phosphine moieties of the Walphos ligands coordinate in one axial and one equatorial position. The differences in the ligand size and the coordination mode between the two types of ligands appear to be reflected in a relative propensity for isomerisation; in solution, the [H4Ru4(CO)10(1,1-Walphos)] clusters isomerise to the corresponding [H4Ru4(CO) 10(μ-1,2-Walphos)] clusters, whereas the Josiphos-containing clusters show no tendency to isomerisation in solution. The clusters have been tested as catalysts for asymmetric hydrogenation of four prochiral α-unsaturated carboxylic acids and the prochiral methyl ester (E)-methyl 2-methylbut-2-enoate. High conversion rates (>94 %) and selectivities of product formation were observed for almost all catalysts/catalyst precursors. The observed enantioselectivities were low or nonexistent for the Josiphos-containing clusters and catalyst (cluster) recovery was low, suggesting that cluster fragmentation takes place. On the other hand, excellent conversion rates (99-100 %), product selectivities (99-100 % in most cases) and good enantioselectivities, reaching 90 % enantiomeric excess (ee) in certain cases, were observed for the Walphos-containing clusters, and the clusters could be recovered in good yield after completed catalysis. Results from high-pressure NMR and IR studies, catalyst poisoning tests and comparison of catalytic properties of two [H4Ru4(CO)10(μ-1,2-P-P)] clusters (P-P=Walphos ligands) with the analogous mononuclear catalysts [Ru(P-P)(carboxylato)2] suggest that these clusters may be the active catalytic species, or direct precursors of an active catalytic cluster species. Copyright
Highly efficient enantioselective synthesis of optically active carboxylic acids by Ru(OCOCH3)2[(S)-H8-BINAP]
Uemura, Toshitsugi,Zhang, Xiaoyoung,Matsumura, Kazuhiko,Sayo, Noboru,Kumobayashi, Hidenori,Ohta, Tetsuo,Nozaki, Kyoko,Takaya, Hidemasa
, p. 5510 - 5516 (1996)
In the presence of a catalytic amount of Ru(OCOCH3)2[(S)-H8-BINAP] [H8-BINAP = 2,2′-bis-(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′- octahydro-1,1′-binaphthyl], the asymmetric hydrogenation of α,β- and β,γ-unsaturated carboxylic acids afforded the corresponding saturated carboxylic acids in higher enantiomeric excesses and at faster reaction rates than those using the Ru(OCOCH3)2[(R)-BINAP] catalyst [BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl]. The hydrogenation of (E)-2-alkyl-2-alkenoic acids by the H8-BINAP catalyst system produced saturated acids in 95-97% ee. 2-Methylcinnamic acid was treated with H8-BINAP-Ru(II) complex as a catalyst to yield a hydrogenated product in much higher ee than that produced by BINAP-Ru(II) (89 and 30% ee, respectively). This homogeneous catalysis using H8-BINAP-Ru(II) established a promising synthetic route to (S)-ibuprofen in up to 97% ee. Asymmetric hydrogenation of β-disubstituted acrylic acids also proceeded smoothly with good enantioselectivities (70-93% ee). In addition, the hydrogenation of trisubstituted acrylic acids (up to 88% ee) was investigated. Hydrogen pressure effect on the sense and level of enantioselection was shown to be substrate dependent. The difference between the H8-BINAP- and BINAP-Ru(II) complexes was also discussed.
A new chiral oxazolidinone derived from diphenylalaninol. Aldol, alkylation, and Diels-Alder reactions
Sibi,Sibi, Mukund P.,Deshpande,Deshpande, Prasad K.,Ji,Jianguo, Ji
, p. 8965 - 8968 (1995)
The chemistry of a new chiral oxazolidinone derived from D-diphenylalaninol is described. Aldol, alkylation, and Diels-Alder reactions using this auxiliary proceed in good chemical and excellent optical yields.
Polysilane-supported Pd and Pt nanoparticles as efficient catalysts for organic synthesis
Oyamada, Hidekazu,Akiyama, Ryo,Hagio, Hiroyuki,Naito, Takeshi,Kobayashi, Shu
, p. 4297 - 4299 (2006)
Polysilane-supported Pd and Pt catalysts have been prepared for the first time, and used successfully in hydrogenation, Suzuki and Sonogashira reactions, and hydrosilylation respectively: the reactions proceeded in high yields, and the catalysts could be recovered almost quantitatively by simple filtration and reused. The Royal Society of Chemistry 2006.
Pd nanoparticles on reverse phase silica gel as recyclable catalyst for Suzuki-Miyaura cross coupling reaction and hydrogenation in water
Shabbir, Saira,Lee, Sinyoung,Lim, Minkyung,Lee, Heejin,Ko, Hyeji,Lee, Youngbok,Rhee, Hakjune
, p. 296 - 304 (2017)
Two catalytic systems, consisting of palladium nanoparticles supported by reverse phase amino functionalized silica are utilized as catalysts for Suzuki-Miyaura reaction and hydrogenation in water. The catalysts were developed by modifying silica into bidentate ligands, using either 2-pyridinecarboxaldehyde or 2,2′-bipyridine-4,4′-dicarboxylic acid. The synthesized catalysts showed quantitative reaction yields and recyclability with negligible leaching of Pd nanoparticles. Various characterization techniques including XPS, ICP-MS, SEM, BET, XRD, TEM, 1H- and 13C- NMR are used to verify the efficiency of the catalysts.
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Harmon et al.
, p. 3684 (1969)
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In-situ ATR-IR investigation of methylcinnamic acid adsorption and hydrogenation on Pd/Al2O3
Sun, Xiaojing,Williams, Christopher T.
, p. 13 - 17 (2012)
The adsorption and hydrogenation of C = C in α-methylcinnamic acid in dichloromethane over the concentration range 2-16 mM have been studied on Al2O3 and Pd/Al2O3 using in-situ attenuated total reflection infrar
Friedel-Crafts Reactions of Ethyl Cyclopropanecarboxylate
Pinnick, Harold W.,Brown, Stephen P.,McLean, Elizabeth A.,Zoller, Linwood W.
, p. 3758 - 3760 (1981)
The reaction of ethyl cyclopropanecarboxylate with benzene in the presence of aluminum chloride gives 2-methyl-1-indanone in excellent yield.
Enantioselective rearrangement coupled with water addition: Direct synthesis of enantiomerically pure saturated carboxylic acids from α,β-unsaturated aldehydes
Winkler, Till,Groeger, Harald,Hummel, Werner
, p. 961 - 964 (2014)
A novel type of organic synthesis enabling a direct one-pot transformation of α,β-unsaturated aldehydes into saturated carboxylic acids is described. As sole reagent water is required, which is integrated completely in the product. This tandem process proceeds under perfect atom economy, and consists of two coupled redox biotransformations without the need of external co-substrates for cofactor regeneration. The initial reduction of the C=C double bond of an α,β-unsaturated aldehyde is catalyzed by an NADPH-dependent ene reductase, leading to the formation of the saturated aldehyde and NADP+. The aldehyde intermediate is then oxidized to the corresponding carboxylic acid, thus regenerating NADPH for the next catalytic cycle. When using prochiral α,β-unsaturated aldehydes as substrates the corresponding carboxylic acids are formed enantioselectively with up to >99 % ee as demonstrated, e.g., for the transformation of citral to (S)-citronellic acid. Making a splash with citral: The direct one-pot transformation of α,β-unsaturated aldehydes to saturated carboxylic acids using only water proceeds with perfect atom economy. This tandem process involves two redox biotransformations without need of additional external co-substrates for cofactor regeneration. With, for example, citral as prochiral α,β-unsaturated aldehyde, transformation to (S)-citronellic acid proceeds with >99 % conversion and >99 % ee.
The application of 1H nuclear magnetic resonance spectroscopy for the determination of the absolute configuration of chiral carboxylic acids
Tyrrell, Elizabeth,Tsang, Michael W. H.,Skinner, George A.,Fawcett, John
, p. 9841 - 9852 (1996)
A modification of a model, described by Mosher allows a correlation to be made between the absolute configuration of a range of simple chiral carboxylic acids with the corresponding nmr chemical shifts of their esters derived from (S)-methyl mandelate.
Modular chiral ligands: The profiling of the Mandyphos and Taniaphos ligand families
Spindler, Felix,Malan, Christophe,Lotz, Matthias,Kesselgruber, Martin,Pittelkow, Ulrich,Rivas-Nass, Andreas,Briel, Oliver,Blaser, Hans-Ulrich
, p. 2299 - 2306 (2004)
A set of 11 ferrocenyl based diphosphine ligands (eight Mandyphos and three Taniaphos) was tested in more than 150 experiments using 20 test reactions. For the assessment of new ligands, a two-pronged strategy was developed consisting of a basic and an extended profiling. The basic profiling showed that the choice of the substituents at the P atoms has a significant effect on the catalyst performance. In the extended profiling it was confirmed that the Mandyphos ligands, in particular M4 with two bis(3,5-dimethyl-4-methoxyphenyl)phosphino groups, and the Taniaphos ligands, especially the all-phenyl derivative T1, showed good to outstanding performances in the hydrogenation of selected α- and β-enamides, acrylic acid derivatives, itaconates, β-ketoesters and 1,3-diketones yielding the corresponding products with up to 99% ee and at substrate/catalyst ratios up to 25,000.
Walphos versus biferrocene-based walphos analogues in the asymmetric hydrogenation of alkenes and ketones
Zirakzadeh, Afrooz,Gross, Manuela A.,Wang, Yaping,Mereiter, Kurt,Weissensteiner, Walter
, p. 1945 - 1952 (2014)
Two representative Walphos analogues with an achiral 2,2″- biferrocenediyl backbone were synthesized. These diphosphine ligands were tested in the rhodium-catalyzed asymmetric hydrogenation of several alkenes and in the ruthenium-catalyzed hydrogenation of two ketones. The results were compared with those previously obtained on using biferrocene ligands with a C 2-symmetric 2,2″-biferrocenediyl backbone as well as with those obtained with Walphos ligands. The application of one newly synthesized ligand in the hydrogenation of 2-methylcinnamic acid gave (R)-2-methyl-3- phenylpropanoic acid with full conversion and with 92% ee. The same ligand was used to transform 2,4-pentanedione quantitatively and diastereoselectively into (S,S)-2,4-pentanediol with 98% ee.
Hydrogenation of Prochiral Olefins with Rhodium Complexes of Optically Active Amidines
Brunner, Henri,Agrifoglio, Giuseppe
, p. 275 - 287 (1980)
2 together with the optically active amidines C6H5C(=NR)NHCH(CH3)(C6H5) I-V or their Li derivatives after activation with molecular hydrogen gives catalysts which at room temperature and 1.1 bar H2-pressure hydrogenate the prochiral substrates (Z)-α-cinnamic acid, itaconic acid, α-methylcinnamic acid, α-methylcinnamic aldehyde, and α-methylcinnamic alcohol as well as cyclohexene, benzene and toluene.Good hydrogenation activity of the new catalysts is in contrast to low optical induction which only in the hydrogenation of α-methylcinnamic alcohol with 1.5 to 2percent leads to values different from zero. - Keywords: Catalytic asymmetric hydrogenation; Optical induction; Rh/amidine complexes
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Watson,M.B.,Youngson,G.W.
, p. 258 - 262 (1968)
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Pd-Catalyzed Regioselective Branched Hydrocarboxylation of Terminal Olefins with Formic Acid
Chu, Jianxiao,Guo, Jianqiong,Ren, Wenlong,Shi, Yian,Shi, Yuan,Wang, Mingzhou,Zhou, Jintao
supporting information, p. 886 - 891 (2022/02/07)
A regioselective Pd-catalyzed hydrocarboxylation of terminal olefins with HCOOH is described. A wide variety of branched carboxylic acids can readily be obtained with high regioselectivities under mild reaction conditions. The reaction is operationally simple and requires no handling of toxic CO. The ligand and LiCl are important factors for reaction reactivity and selectivity.
Photoredox Activation of Formate Salts: Hydrocarboxylation of Alkenes via Carboxyl Group Transfer
Huang, Yan,Hou, Jing,Zhan, Le-Wu,Zhang, Qian,Tang, Wan-Ying,Li, Bin-Dong
, p. 15004 - 15012 (2021/12/14)
A photoredox activation mode of formate salts for carboxylation was developed. Using a formate salt as the reductant, carbonyl source, and hydrogen atom transfer reagent, a wide range of alkenes can be converted into acid products via a carboxyl group tra
