- Gas-phase pyrolytic reaction of 3-phenoxy and 3-phenylsulfanyl-1-propanol derivatives: Kinetic and mechanistic study
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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.
- Dib,Ibrahim,Al-Awadi,Ibrahim,Al-Awadi
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- Bifunctional Catalysts for Regioselective Hydrogenation and for Hydrogenation of Highly-substituted Alkenes
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catalyses the hydrogenation of highly-substituted acrylic acids in the presence of base by a mechanism involving chelate stabilisation of alkene co-ordination and base-catalysed transesteification of the co-ordinated mixed anhydride; for hexa-2,4-dienoic acid, selective hydrogenation of the αβ double bond occurs.
- Preston, Sheila A.,Cupertino, Domenico C.,Palma-Ramirez, Pilar,Cole-Hamilton, David J.
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- Model Studies on the Enzyme-Regulated Stereodivergent Cascade Passerini Reaction
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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.
- Brodzka, Anna,Koszelewski, Dominik,Ostaszewski, Ryszard,Samsonowicz-Górski, Jan,Wilk, Monika
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- RHODIUM(I) COMPLEXES OF FERROCENYLPHOSPHINES AS EFFICIENT ASYMMETRIC CATALYSTS. THE STRUCTURE OF Fe(η5-C5H3(P(CMe3)2-1,3)(η5-C5H3(CHMeNMe2)(P(CMe3)2-1,2)
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Rhodium(I) complexes of the chiral ligands Fe(η5-C5H5-n(P(CMe3)2)n-1,3)(η5-C5H3(CHMeNMe2)P(CMe3)2-1,2 (n=0-2) are P-N bound, and are asymmetric hydrogenation catalysts.The configuration of the product from prochiral olefins is controlled by the planar chirality of the ligand.The catalyst with n=2 is the most efficient affording optical yields as good as those obtained from more conventional systems embodying PAr2 donors.Crystals of the ligand n=2 are monoclinic, P21, a 11.448(4), b 44.667(7), c 8.669(3) Angsroem, β 111.98(1), V 4111(2) Angstroem, Z=4 (2 molecules per asymmetric unit) Dx 1.114, Dm 1.129 g cm-3 (by flotation in aqueous KI), final R=0.069 for 4799 observed reflections.The molecule is chiral, with an (S,S) configuration, and the two crystallographically independent molecules have almost identical geometries and conformations.The cyclopentadienyl rings are close to planar, deviate slightly from coplanarity, and are rotated by about 7 deg from an eclipsed conformation; the substituent P and C atoms are significantly displaced from the ring planes.Fe-C bond length average 2.044 and 2.092 Angstroem to unsubstituted C atoms, respectively.
- Appelton, Trevor D.,Cullen, William R.,Evans, Sthephen,Kim, Tae-Jeong,Trotter, James
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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
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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.
- Lee, Jong-Dae,Thanh, Thien Co,Kim, Tae-Jeong,Sang, Ook Kang
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- Ferrocenyl chiral bisphosphorus ligands for highly enantioselective asymmetric hydrogenation via noncovalent ion pair interaction
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A new class of ferrocenyl chiral bisphosphorus ligand, Wudaphos, was developed, and exhibits excellent ee and activity (ee up to 99%, TON up to 20000) for the asymmetric hydrogenation of both 2-aryl and 2-alkyl acrylic acids through ion pair noncovalent interaction under base free and mild reaction conditions. Well-known anti-inflammatory drugs such as naproxen and ibuprofen together with the intermediate for the preparation of Roche ester and some bioactive compounds were also efficiently obtained with excellent ee. Control experiments were conducted and revealed that the ion pair noncovalent interaction and chain length played important roles.
- Chen, Caiyou,Wang, Heng,Zhang, Zhefan,Jin, Shicheng,Wen, Songwei,Ji, Jianjian,Chung, Lung Wa,Dong, Xiu-Qin,Zhang, Xumu
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- Enantioselective Hydrogenation of α-Methylcinnamic Acid over Pd/Al2O3: A Kinetic Study of Solvent, Temperature and Pressure Effects
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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.]
- Sun, Xiaojing,Monnier, John R.,Williams, Christopher T.
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- Regioselectivity inversion tuned by iron(iii) salts in palladium-catalyzed carbonylations
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Impactful regioselectivity control is crucial for cost-effective chemical synthesis. By using cheap and abundant iron(iii) salts, the hydroxycarbonylations of both aromatic and aliphatic alkenes were significantly enhanced in both reactivity and selectivity (iso/n or n/iso up to >99:1). Moreover, Pd-catalyzed carbonylation selectivity can be switched from branched to linear by using different Fe(iii) salts. In addition, similar results were obtained for the carbonylation of secondary alcohols.
- Huang, Zijun,Cheng, Yazhe,Chen, Xipeng,Wang, Hui-Fang,Du, Chen-Xia,Li, Yuehui
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- COPPER-CATALYZED REACTION OF GRIGNARD REAGENTS WITH β-PROPIOLACTONES: A CONVENIENT METHOD FOR THE SYNTHESIS OF Β-SUBSTITUTED PROPIONIC ACIDS
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Grignard reagents react with β-propiolactones in the presence of a copper(I) catalyst to give β-substituted propionic acids in high yields.
- Sato, Toshio,Kawara, Tatsuo,Kawashima, Masatoshi,Fujisawa, Tamotsu
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- A THREE CARBON HOMOLOGATION BY THE RING-OPENING OF β-PROPIOLACTONES WITH DIORGANOCUPRATES
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Various organocuprates react with β-propiolactones to give β-substituted propionic acids in high yields.
- Fujisawa, Tamotsu,Sato, Toshio,Kawara, Tatsuo,Kawashima, Masatoshi
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- Acceleration of enantioselective hydrogenation of olefins over Pd/C by cinchonidine as a chiral modifier. Comparison with cinchonine, pseudoenantiomer
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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.
- Sugimura, Takashi,Ogawa, Hiroyuki
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- Pd nanoparticles dispersed on solid supports: Synthesis, characterization and catalytic activity on selective hydrogenation of olefins in aqueous media
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Two types of Pd nanoparticle catalysts were prepared having 2-4 nm particle size using silica gel and porous polymer beads as solid supports. 2-Pyridinecarboxaldehyde ligand was anchored on commercially available 3-aminopropyl-functionalized silica gel followed by Pd metal dispersion. Bead-shaped cross-linked poly(4-vinylpyridine-co-styrene) gel was prepared by an emulsifier-free emulsion polymerization of 4-vinylpyridine, styrene and divinylbenzene in the presence of ammonium persulfate and subsequently dispersing the Pd metal on the synthesized polymer. These catalysts were characterized by SEM, TEM and ICP techiniques with respect to appearance, size and possible leaching out, respectively. Furthermore, the reactivity of these catalysts was tested on hydrogenation of various α,β-unsaturated carbonyl compounds using aqueous solvent under a hydrogen balloon (1 atm). The results showed that the Pd dispersed on silica was a more efficient catalyst than Pd dispersed on polymer and the former could be recycled more than 10 times without considerable loss in activity. Copyright
- Lim, Minkyung,De Castro, Kathlia A.,Oh, Seungchan,Lee, Kangsuk,Chang, Young-Wook,Kim, Hokun,Rhee, Hakjune
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- Hydrogenation and dehalogenation under aqueous conditions with an amphiphilic-polymer-supported nanopalladium catalyst
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(Chemical Equation Presented) An amphiphilic polystyrene-poly(ethylene glycol) resin supported nanopalladium particle catalyzed hydrogenation of olefins and hydrodechlorination of chloroarenes under aqueous conditions is presented.
- Nakao, Ryu,Rhee, Hakjune,Uozumi, Yasuhiro
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- Magnetic nanoparticles entrapped in siliceous mesocellular foam: A new catalyst support
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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
- Lee, Su Seong,Riduan, Siti Nurhanna,Erathodiyil, Nandanan,Lim, Jaehong,Cheong, Jian Liang,Cha, Junhoe,Han, Yu,Ying, Jackie Y.
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- Oxidative rearrangement of malondialdehyde: Substrate scope and mechanistic insights
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A novel oxidative rearrangement of malondialdehyde was described. Under the effect of H2O2, malondialdehyde smoothly transferred to carboxylic acid with C-C bond cleavage in good to excellent yields. Mechanistic studies showed that this reaction proceeded via the formation of a 1,2-dioxolane intermediate, followed by concert C-C, O-O, C-H bond cleavage and a hydride shift.
- Yu, Xin,Liu, Zheng,Xia, Zilei,Shen, Zhigao,Pan, Xixian,Zhang, Hui,Xie, Weiqing
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- Asymmetric aldol and alkylation reactions mediated by the 'quat' chiral auxiliary (R)-(-)-5-methyl-3,3-dimethyl-2-pyrrolidinone
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Enolates derived from the N-propionoyl derivative of the 'quat' chiral auxiliary (R)-(-)-5-methyl-3,3-dimethyl-2-pyrrolidinone undergo highly stereoselective aldol and alkylation reactions. Removal of the auxiliary has been demonstrated with LiOH, PhCH2OLi, MeOMgBr and LiAlH4 to generate respectively (2R,3R)-3-hydroxy-2-methyl-3-phenylpropionic acid in homochiral form, and with 96% e.e. (S)-2-methyl-3-phenylpropionic acid and derived methyl and benzyl esters and with >94% e.e. (S)-2-methyl-3-phenylpropanol.
- Davies,Doisneau,Prodger,Sanganee
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- Efficient cluster-based catalysts for asymmetric hydrogenation of α-unsaturated carboxylic acids
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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
- 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
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p. 12458 - 12478,21
(2012)
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- Phenol-derived chiral phosphine-phosphite ligands in the rhodium-catalyzed enantioselective hydrogenation of functionalized olefins
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A set of 15 chiral Taddol- and Binol-based phosphine-phosphite ligands were tested in the Rh-catalyzed asymmetric hydrogenation of three olefins, methyl 2-hydroxymethyl-acrylate, 1-phenylvinyl acetate, and α-methyl cinnamic acid. The best enantioselectivities (up to 92% ee) were observed in the hydrogenation of methyl 2-hydroxymethyl-acrylate using Binol-based ligands. As previously observed in other applications of this class of modular chiral ligand in enantioselective catalysis, the stereochemical outcome of the reactions greatly depended on the substituents at the ligand aryl backbone in the ortho-position to the chiral phosphite unit.
- Robert, Tobias,Abiri, Zohar,Sandee, Albertus J.,Schmalz, Hans-Guenther,Reek, Joost N.H.
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- Highly efficient enantioselective synthesis of optically active carboxylic acids by Ru(OCOCH3)2[(S)-H8-BINAP]
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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.
- Uemura, Toshitsugi,Zhang, Xiaoyoung,Matsumura, Kazuhiko,Sayo, Noboru,Kumobayashi, Hidenori,Ohta, Tetsuo,Nozaki, Kyoko,Takaya, Hidemasa
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- Biferrocene-based diphosphine ligands: Synthesis and application of walphos analogues in asymmetric hydrogenations
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A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments (R)-1-(N,N-dimethylamino)ethylferrocene and (SFc)-2- bromoiodoferrocene. The molecular structures of (SFc)-2- bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl2(L)] and [RuCl(p-cymene)(L)]PF6) were determined by X-ray diffraction. The structural features of complexes and the catalysis results obtained with the newly synthesized biferrocene-based ligands were compared with those of the corresponding Walphos ligands.
- Zirakzadeh, Afrooz,Gross, Manuela A.,Wang, Yaping,Mereiter, Kurt,Spindler, Felix,Weissensteiner, Walter
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- A new chiral oxazolidinone derived from diphenylalaninol. Aldol, alkylation, and Diels-Alder reactions
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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.
- Sibi,Sibi, Mukund P.,Deshpande,Deshpande, Prasad K.,Ji,Jianguo, Ji
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- Polysilane-supported Pd and Pt nanoparticles as efficient catalysts for organic synthesis
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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.
- Oyamada, Hidekazu,Akiyama, Ryo,Hagio, Hiroyuki,Naito, Takeshi,Kobayashi, Shu
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- Pd nanoparticles on reverse phase silica gel as recyclable catalyst for Suzuki-Miyaura cross coupling reaction and hydrogenation in water
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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.
- Shabbir, Saira,Lee, Sinyoung,Lim, Minkyung,Lee, Heejin,Ko, Hyeji,Lee, Youngbok,Rhee, Hakjune
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- SYNTHESIS OF CHIRAL BUILDING BLOCKS FOR SELECTIVE ADENOSINE RECEPTOR AGENTS. LIPASE-CATALYZED RESOLUTION OF 2-BENZYLPROPANOL AND 2-BENZYLPROPIONIC ACID
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Both enantiomers of 2-benzylpropanol and 2-benzylpropinoic acid have been synthesized using a lipase-catalyzed resolution in an organic solvent and in water.
- Delnick, Deborah L.,Margolin, Alexey L.
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- Chirality control by the aid of 2,2-dimethyloxazolidine chiral auxiliaries. Highly 1,4-chiral inductive asymmetric alkylations of amide enolates
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The propanamide and methoxyacetamide derivatives of (S)-4-benzyl-2,2,5,5-tetramethyloxazolidine, a new chirality controlling auxiliary based on the restricted rotation around amide bond, generate chiral lithium Z-enolates by lithiation. They undergo highly lk-1,4- and ul-1,4-inductive alkylations with a variety of alkylating reagents, respectively. The diastereotopic face participated in the reactions is that remote from the 4-shielding substituent of oxazolidine in the syn-conformations. Coplanarity between the enolate double bond and the oxazolidine plane in the transition state can be a major factor for the observed excellent selectivities.
- Kanemasa,Ueno,Onimura,Kikukawa,Yamamoto
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- In-situ ATR-IR investigation of methylcinnamic acid adsorption and hydrogenation on Pd/Al2O3
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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
- Sun, Xiaojing,Williams, Christopher T.
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- Chemoselective Catalytic Dehydrogenative Cross-Coupling of 2-Acylimidazoles: Mechanistic Investigations and Synthetic Scope
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Chemoselective iron-catalyzed dehydrogenative cross-coupling using 2-acylimidazoles is described. The addition of a phosphine oxide ligand substantially facilitated the generation of tert-butoxy radicals from di-tert-butyl peroxide, allowing for efficient benzylic C-H bond cleavage under mild conditions. Extensive mechanistic studies revealed that the enolization of 2-acylimidazole proceeded through dual iron catalyst activation, followed by subsequent chemoselective cross-coupling with a benzyl radical over an undesired benzyl radical-derived homocoupling dimer that inevitably formed in earlier reported conditions. A variety of alkylarenes, aliphatic alkane, and functionalized 2-acylimidazoles were applicable, demonstrating the synthetic utility of the present catalysis. Contiguous all-carbon quaternary carbons were constructed through dehydrogenative cross-coupling. The catalytic chemoselective activation of 2-acylimidazole over bidentate coordinative and much more acidic malonate diester was particular noteworthy. Catalytic oxidative cross-enolate coupling of two distinct carboxylic acid equivalents was also achieved using acetonitrile as a coupling partner.
- Tanaka, Tsukushi,Hashiguchi, Kayoko,Tanaka, Takafumi,Yazaki, Ryo,Ohshima, Takashi
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- Friedel-Crafts Reactions of Ethyl Cyclopropanecarboxylate
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The reaction of ethyl cyclopropanecarboxylate with benzene in the presence of aluminum chloride gives 2-methyl-1-indanone in excellent yield.
- Pinnick, Harold W.,Brown, Stephen P.,McLean, Elizabeth A.,Zoller, Linwood W.
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- Application of ionic liquids in palladium(II) catalyzed homogenous transfer hydrogenation
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The first application of palladium(II) catalyzed homogenous transfer hydrogenations in ionic liquids is described. Cinnamic acid and its derivatives were reduced in high yields under mild conditions using ammonium formate as hydrogen donor.
- Baán, Zoltán,Finta, Zoltán,Keglevich, Gy?rgy,Hermecz, István
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- Enantioselective rearrangement coupled with water addition: Direct synthesis of enantiomerically pure saturated carboxylic acids from α,β-unsaturated aldehydes
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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.
- Winkler, Till,Groeger, Harald,Hummel, Werner
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- Use of ethyl (benzothiazol-2-ylsulfonyl)acetate for malonic ester-type syntheses of carboxylic acids and esters
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A new methodology for the synthesis of substituted carboxylic acids is described. Alkylation of either ethyl (benzothiazol-2-ylsulfonyl)acetate or ethyl 2-(benzothiazol-2-ylsulfonyl)propionate was achieved with alkyl halides and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane solution. These products were then desulfinated and hydrolysed in one-pot under mild conditions to give substituted acetic acids in good-to-excellent yields.
- Hussein, Waleed M.,McGeary, Ross P.
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- The application of 1H nuclear magnetic resonance spectroscopy for the determination of the absolute configuration of chiral carboxylic acids
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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.
- Tyrrell, Elizabeth,Tsang, Michael W. H.,Skinner, George A.,Fawcett, John
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- P-Stereogenic diphosphines in the ruthenium-catalysed asymmetric hydrogenation of C=C and C=O double bonds
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Bis(acetato) and dichloro complexes of ruthenium(II) containing P-stereogenic ligands have been prepared and tested in the asymmetric catalytic hydrogenation of functionalised olefins and keto esters. The best performance (52.6% ee) has been obtained in the hydrogenation of ethyl acetoacetate with [RuCl(PPh3)((S,S)-1,1′-bis(1-naphthylphenylphosphino) ferrocene)] 4.
- Maienza, Francesca,Santoro, Francesco,Spindler, Felix,Malan, Christophe,Mezzetti, Antonio
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- Modular chiral ligands: The profiling of the Mandyphos and Taniaphos ligand families
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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.
- Spindler, Felix,Malan, Christophe,Lotz, Matthias,Kesselgruber, Martin,Pittelkow, Ulrich,Rivas-Nass, Andreas,Briel, Oliver,Blaser, Hans-Ulrich
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- Catalytic transfer hydrogenation and hydrogenolysis in ionic liquids with Pd/MgLa mixed oxide and Pd/MgAl hydrotalcite as recyclable catalysts
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A new Pd/MgLa mixed oxide and the known Pd/MgAl hydrotalcite catalysts were applied and recycled successfully in catalytic transfer hydrogenation reactions in ionic liquids. Some α,β-unsaturated carboxylic acid derivatives were hydrogenated in excellent yields. The catalysts were recycled without significant loss of activity. Besides that, a number of halogenated aromatic compounds were dehalogenated under similar catalytic transfer conditions. Copyright Taylor & Francis Group, LLC.
- Baan, Zoltan,Potor, Attila,Cwik, Agnieszka,Hell, Zoltan,Keglevich, Gyoergy,Finta, Zoltan,Hermecz, Istvan
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- Walphos versus biferrocene-based walphos analogues in the asymmetric hydrogenation of alkenes and ketones
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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.
- Zirakzadeh, Afrooz,Gross, Manuela A.,Wang, Yaping,Mereiter, Kurt,Weissensteiner, Walter
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- Design, synthesis and biological evaluation of tetrazole-containing RXRα ligands as anticancer agents
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Nuclear receptor RXRα plays an important role in many biological and pathological processes. The nongenomic action of RXRα is implicated in many cancers. K-8008, a non-canonical RXRα ligand derived from sulindac, inhibits the TNFα-activated PI3K/AKT pathway by mediating the interaction between a truncated form of RXRα (tRXRα) and the p85α regulatory subunit of PI3K and exerts potent anticancer activity in animal model. Herein we report our studies of a novel series of K-8008 analogs as potential anticancer agents targeting RXRα. Two compounds 8b and 18a were identified to have slightly stronger binding to RXRα and improved apoptotic activities in breast cancer cells.
- Yan, Zhiqiang,Chong, Shuyi,Lin, Huiyun,Yang, Qian,Wang, Xin,Zhang, Weidong,Zhang, Xiaokun,Zeng, Zhiping,Su, Ying
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- Hydrogenation of Prochiral Olefins with Rhodium Complexes of Optically Active Amidines
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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
- Brunner, Henri,Agrifoglio, Giuseppe
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- Conjugate addition of organolithium reagents to α,β-unsaturated carbocyclic acids
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Conjugate addition of primary, secondary, tertiary alkyi and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.
- Aurell, Maria Jose,Domingo, Luis Ramon,Mestres, Ramon,Munos, Elena,Zaragoza, Ramon Jose
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- Pd-Catalyzed Regioselective Branched Hydrocarboxylation of Terminal Olefins with Formic Acid
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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.
- Chu, Jianxiao,Guo, Jianqiong,Ren, Wenlong,Shi, Yian,Shi, Yuan,Wang, Mingzhou,Zhou, Jintao
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supporting information
p. 886 - 891
(2022/02/07)
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- Catalytic α-Deracemization of Ketones Enabled by Photoredox Deprotonation and Enantioselective Protonation
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This study reports the catalytic deracemization of ketones bearing stereocenters in the α-position in a single reaction via deprotonation, followed by enantioselective protonation. The principle of microscopic reversibility, which has previously rendered this strategy elusive, is overcome by a photoredox deprotonation through single electron transfer and subsequent hydrogen atom transfer (HAT). Specifically, the irradiation of racemic pyridylketones in the presence of a single photocatalyst and a tertiary amine provides nonracemic carbonyl compounds with up to 97% enantiomeric excess. The photocatalyst harvests the visible light, induces the redox process, and is responsible for the asymmetric induction, while the amine serves as a single electron donor, HAT reagent, and proton source. This conceptually simple light-driven strategy of coupling a photoredox deprotonation with a stereocontrolled protonation, in conjunction with an enrichment process, serves as a blueprint for other deracemizations of ubiquitous carbonyl compounds.
- Chen, Shuming,Gao, Anthony Z.,Ivlev, Sergei I.,Meggers, Eric,Nie, Xin,Ye, Chen-Xi,Zhang, Chenhao
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supporting information
p. 13393 - 13400
(2021/09/03)
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- Chemoselective reduction of ?,¢-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
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The selective reduction of ?,¢-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ¢ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ¢-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
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p. 590 - 599
(2021/03/29)
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- Photoredox Activation of Formate Salts: Hydrocarboxylation of Alkenes via Carboxyl Group Transfer
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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
- Huang, Yan,Hou, Jing,Zhan, Le-Wu,Zhang, Qian,Tang, Wan-Ying,Li, Bin-Dong
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p. 15004 - 15012
(2021/12/14)
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- Suppressing carboxylate nucleophilicity with inorganic salts enables selective electrocarboxylation without sacrificial anodes
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Although electrocarboxylation reactions use CO2as a renewable synthon and can incorporate renewable electricity as a driving force, the overall sustainability and practicality of this process is limited by the use of sacrificial anodes such as magnesium and aluminum. Replacing these anodes for the carboxylation of organic halides is not trivial because the cations produced from their oxidation inhibit a variety of undesired nucleophilic reactions that form esters, carbonates, and alcohols. Herein, a strategy to maintain selectivity without a sacrificial anode is developed by adding a salt with an inorganic cation that blocks nucleophilic reactions. Using anhydrous MgBr2as a low-cost, soluble source of Mg2+cations, carboxylation of a variety of aliphatic, benzylic, and aromatic halides was achieved with moderate to good (34-78%) yields without a sacrificial anode. Moreover, the yields from the sacrificial-anode-free process were often comparable or better than those from a traditional sacrificial-anode process. Examining a wide variety of substrates shows a correlation between known nucleophilic susceptibilities of carbon-halide bonds and selectivity loss in the absence of a Mg2+source. The carboxylate anion product was also discovered to mitigate cathodic passivation by insoluble carbonates produced as byproducts from concomitant CO2reduction to CO, although this protection can eventually become insufficient when sacrificial anodes are used. These results are a key step toward sustainable and practical carboxylation by providing an electrolyte design guideline to obviate the need for sacrificial anodes.
- Corbin, Nathan,Lazouski, Nikifar,Manthiram, Karthish,Steinberg, Katherine,Yang, Deng-Tao
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p. 12365 - 12376
(2021/10/08)
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- Photoinduced Hydrocarboxylation via Thiol-Catalyzed Delivery of Formate across Activated Alkenes
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Herein we disclose a new photochemical process to prepare carboxylic acids from formate salts and alkenes. This redox-neutral hydrocarboxylation proceeds in high yields across diverse functionalized alkene substrates with excellent regioselectivity. This operationally simple procedure can be readily scaled in batch at low photocatalyst loading (0.01% photocatalyst). Furthermore, this new reaction can leverage commercially available formate carbon isotologues to enable the direct synthesis of isotopically labeled carboxylic acids. Mechanistic studies support the working model involving a thiol-catalyzed radical chain process wherein the atoms from formate are delivered across the alkene substrate via CO2?- as a key reactive intermediate.
- Alektiar, Sara N.,Wickens, Zachary K.
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supporting information
p. 13022 - 13028
(2021/09/03)
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- Direct 3-Acylation of Indolizines by Carboxylic Acids for the Practical Synthesis of Red Light-Releasable Caged Carboxylic Acids
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To enhance the practicality of photouncaging system using 3-acyl-2-methoxyindolizines, direct acylation of indolizines with carboxylic acids was developed using condensation reagents, generally used for peptide coupling. This method allowed for caging a broad range of carboxylic acids with indolizines. The method enabled a facile synthesis of water-soluble caged bioactive carboxylic acids having an intramolecular photosensitizer. The efficient release of carboxylic acids from the synthesized caged compounds upon red light irradiation was confirmed in neutral buffered solutions.
- Watanabe, Kenji,Terao, Nodoka,Niwa, Takashi,Hosoya, Takamitsu
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p. 11822 - 11834
(2021/07/31)
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- 1,3,2-Diazaphospholenes Catalyze the Conjugate Reduction of Substituted Acrylic Acids
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The potent nucleophilicity and remarkably low basicity of 1,3,2-diazaphospholenes (DAPs) is exploited in a catalytic, metal-free 1,4-reduction of free α,β-unsaturated carboxylic acids. Notably, the reduction occurs without a prior deprotonation of the carboxylic acid moiety and hence does not consume an additional hydride equivalent. This highlights the excellent nucleophilic character and low basicity of DAP-hydrides. Functional groups such as Cbz group or alkyl halides which can be problematic with classical transition-metal catalysts are well tolerated in the DAP-catalyzed process. Moreover, the transformation is characterized by a low catalyst loading, mild reaction conditions at ambient temperature as well as fast reaction times and high yields. The proof-of-principle for a catalytic enantioselective version is described.
- Reed, John H.,Cramer, Nicolai
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p. 4262 - 4266
(2020/07/13)
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- Cobalt-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Carboxylic Acids by Homolytic H2 Cleavage
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The asymmetric hydrogenation of α,β-unsaturated carboxylic acids using readily prepared bis(phosphine) cobalt(0) 1,5-cyclooctadiene precatalysts is described. Di-, tri-, and tetra-substituted acrylic acid derivatives with various substitution patterns as well as dehydro-α-amino acid derivatives were hydrogenated with high yields and enantioselectivities, affording chiral carboxylic acids including Naproxen, (S)-Flurbiprofen, and a d-DOPA precursor. Turnover numbers of up to 200 were routinely obtained. Compatibility with common organic functional groups was observed with the reduced cobalt(0) precatalysts, and protic solvents such as methanol and isopropanol were identified as optimal. A series of bis(phosphine) cobalt(II) bis(pivalate) complexes, which bear structural similarity to state-of-the-art ruthenium(II) catalysts, were synthesized, characterized, and proved catalytically competent. X-band EPR experiments revealed bis(phosphine)cobalt(II) bis(carboxylate)s were generated in catalytic reactions and were identified as catalyst resting states. Isolation and characterization of a cobalt(II)-substrate complex from a stoichiometric reaction suggests that alkene insertion into the cobalt hydride occurred in the presence of free carboxylic acid, producing the same alkane enantiomer as that from the catalytic reaction. Deuterium labeling studies established homolytic H2 (or D2) activation by Co(0) and cis addition of H2 (or D2) across alkene double bonds, reminiscent of rhodium(I) catalysts but distinct from ruthenium(II) and nickel(II) carboxylates that operate by heterolytic H2 cleavage pathways.
- Chirik, Paul J.,Shevlin, Michael,Zhong, Hongyu
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supporting information
(2020/03/13)
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- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0061-0064
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- Method for selective reduction α, β - unsaturated carbonyl compound carbon-carbon double bond (by machine translation)
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The invention discloses a method for selectively reducing carbon-carbon double bonds in α and β - unsaturated carbonyl compounds, which comprises the following steps of adding α, β - unsaturated carbonyl compounds shown in formula (I) in an electrolysis system and reducing α and β - unsaturated carbonyl compounds with carbonyl-conjugated carbon-carbon double bonds through an electrochemical cathodic reduction reaction. Compared with the reported method, the method disclosed by the invention does not use a metal catalyst and an external oxidant; and the reaction raw material and the electrolyte are low in price, nontoxic and tasteless, simple and convenient in post-treatment. (by machine translation)
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Paragraph 0067-0070
(2020/06/17)
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- Environmentally responsible, safe, and chemoselective catalytic hydrogenation of olefins: ppm level Pd catalysis in recyclable water at room temperature
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Textbook catalytic hydrogenations are typically presented as reactions done in organic solvents and oftentimes under varying pressures of hydrogen using specialized equipment. Catalysts new and old are all used under similar conditions that no longer reflect the times. By definition, such reactions are both environmentally irresponsible and dangerous, especially at industrial scales. We now report on a general method for chemoselective and safe hydrogenation of olefins in water using ppm loadings of palladium from commercially available, inexpensive, and recyclable Pd/C, together with hydrogen gas utilized at 1 atmosphere. A variety of alkenes is amenable to reduction, including terminal, highly substituted internal, and variously conjugated arrays. In most cases, only 500 ppm of heterogeneous Pd/C is sufficient, enabled by micellar catalysis used in recyclable water at room temperature. Comparison with several newly introduced catalysts featuring base metals illustrates the superiority of chemistry in water.
- Gallou, Fabrice,Gao, Eugene S.,Lipshutz, Bruce H.,Takale, Balaram S.,Thakore, Ruchita R.
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supporting information
p. 6055 - 6061
(2020/10/14)
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- Electrocatalytic asymmetric hydrogenation of α,β-unsaturated acids in a PEM reactor with cinchona-modified palladium catalysts
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We have developed an electrocatalytic asymmetric hydrogenation reaction using a proton-exchange membrane (PEM) reactor that employs a polymer electrolyte fuel cell and industrial electrolysis technologies. Reasonable enantioselectivities and excellent current efficiencies were obtained in the asymmetric hydrogenation of α-phenylcinnamic acid under mild conditions without adding a supporting electrolyte. The current density was crucial to achieving the improved results observed.
- Atobe, Mahito,Fukazawa, Atsushi,Hashimoto, Yasushi,Sato, Yasushi,Tanaka, Kenta
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- Palladium-Catalyzed C(sp3)-H Nitrooxylation with tert-Butyl Nitrite and Molecular Oxygen
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Herein, we report a Pd(II)-catalyzed nitrooxylation of unactivated methyl C(sp3)-H bonds using commercial available and easily manageable tert-butyl nitrite as the precursor of ONO2 radical under aerobic conditions. Environmentally benign molecular oxygen is used to initiate the generation of active radical reactant; it is also used as the terminal oxidant. A broad range of nitrooxylated aliphatic carboxamides were prepared in moderate to good yields under mild conditions.
- Han, Ye-Qiang,Li, Bo,Shi, Bing-Feng,Yang, Xu
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supporting information
p. 9719 - 9723
(2020/12/21)
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- Harnessing Applied Potential: Selective β-Hydrocarboxylation of Substituted Olefins
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The construction of carboxylic acid compounds in a selective fashion from low value materials such as alkenes remains a long-standing challenge to synthetic chemists. In particular, β-addition to styrenes is underdeveloped. Herein we report a new electrosynthetic approach to the selective hydrocarboxylation of alkenes that overcomes the limitations of current transition metal and photochemical approaches. The reported method allows unprecedented direct access to carboxylic acids derived from β,β-trisubstituted alkenes, in a highly regioselective manner.
- Alkayal, Anas,Buckley, Benjamin R.,Malkov, Andrei V.,Montanaro, Stephanie,Tabas, Volodymyr,Wright, Iain A.
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supporting information
(2020/02/13)
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- Deracemizing α-Branched Carboxylic Acids by Catalytic Asymmetric Protonation of Bis-Silyl Ketene Acetals with Water or Methanol
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We report a highly enantioselective catalytic protonation of bis-silyl ketene acetals. Our method delivers α-branched carboxylic acids, including nonsteroidal anti-inflammatory arylpropionic acids such as Ibuprofen, in high enantiomeric purity and high yields. The process can be incorporated in an overall deracemization of α-branched carboxylic acids, involving a double deprotonation and silylation followed by the catalytic asymmetric protonation.
- Mandrelli, Francesca,Blond, Aurélie,James, Thomas,Kim, Hyejin,List, Benjamin
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p. 11479 - 11482
(2019/07/18)
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- Carbonylative Transformation of Allylarenes with CO Surrogates: Tunable Synthesis of 4-Arylbutanoic Acids, 2-Arylbutanoic Acids, and 4-Arylbutanals
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In this Communication, procedures for the selective synthesis of 4-arylbutanoic acids, 2-arylbutanoic acids, and 4-arylbutanals from the same allylbenzenes have been developed. With formic acid or TFBen as the CO surrogate, reactions proceed selectively and effectively under carbon monoxide gas-free conditions.
- Wu, Fu-Peng,Li, Da,Peng, Jin-Bao,Wu, Xiao-Feng
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supporting information
p. 5699 - 5703
(2019/08/01)
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- Synthesis of Carboxylic Acids by Palladium-Catalyzed Hydroxycarbonylation
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The synthesis of carboxylic acids is of fundamental importance in the chemical industry and the corresponding products find numerous applications for polymers, cosmetics, pharmaceuticals, agrochemicals, and other manufactured chemicals. Although hydroxycarbonylations of olefins have been known for more than 60 years, currently known catalyst systems for this transformation do not fulfill industrial requirements, for example, stability. Presented herein for the first time is an aqueous-phase protocol that allows conversion of various olefins, including sterically hindered and demanding tetra-, tri-, and 1,1-disubstituted systems, as well as terminal alkenes, into the corresponding carboxylic acids in excellent yields. The outstanding stability of the catalyst system (26 recycling runs in 32 days without measurable loss of activity), is showcased in the preparation of an industrially relevant fatty acid. Key-to-success is the use of a built-in-base ligand under acidic aqueous conditions. This catalytic system is expected to provide a basis for new cost-competitive processes for the industrial production of carboxylic acids.
- Sang, Rui,Kucmierczyk, Peter,Dühren, Ricarda,Razzaq, Rauf,Dong, Kaiwu,Liu, Jie,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 14365 - 14373
(2019/09/06)
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- Preparation method for indanone compound
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The invention especially relates to a preparation method for an indanone compound, belonging to the field of organic synthesis. The preparation method for the indanone compounds comprises the following steps: 1) subjecting a compound as shown in a formula I and a compound as shown in a formula II to a condensation reaction so as to prepare a compound as shown in a formula III; 2) subjecting the compound as shown in the formula III to hydrolysis in the presence of alkali so as to prepare a compound as shown in a formula IV; and 3) carrying out acylation and ring closure on the compound as shownin the formula IV so as to prepare the as shown in a formula V. Compared with the prior art, the preparation method for the indanone compound in the invention has the advantages of low raw material cost, simple operation, low production of waste water, waste gas and industrial residues, high yield and the like, and is more suitable for industrial production; and compared with various traditionalpreparation methods for the indanone compound, the preparation method of the invention has obvious advantages and shows good industrialization prospects.
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Paragraph 0087; 0090
(2018/08/28)
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- Weak, bidentate chelating group assisted cross-coupling of C(sp3)-H bonds in aliphatic acid derivatives with aryltrifluoroborates
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A protocol of Pd(ii)-catalyzed, weak bidentate directing group assisted β-C(sp3)-H activation/cross-coupling with organoboron reagents has been achieved, affording arylation of aliphatic acid derivatives that contain α-hydrogen atoms in moderate to good yields. The potential of this method for an asymmetric β-C(sp3)-H arylation via desymmetrization was also presented.
- Cai, Zhihua,Li, Shangda,Gao, Yuzhen,Fu, Lei,Li, Gang
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supporting information
p. 12766 - 12769
(2018/11/23)
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- Synthesis of Bicyclo[n.1.0]alkanes by a Cobalt-Catalyzed Multiple C(sp3)?H Activation Strategy
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A cobalt-catalyzed dual C(sp3)?H activation strategy has been developed and it provides a novel strategy for the synthesis of bicyclo[4.1.0]heptanes and bicyclo[3.1.0]hexanes. A key to the success of this reaction is the conformation-induced methylene C(sp3)?H activation of the resulting cobaltabicyclo[4.n.1] intermediate. In addition, the synthesis of bicyclo[3.1.0]hexane from pivalamide, by a triple C(sp3)?H activation, has also been demonstrated.
- Zhang, Zhuo-Zhuo,Han, Ye-Qiang,Zhan, Bei-Bei,Wang, Sai,Shi, Bing-Feng
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supporting information
p. 13145 - 13149
(2017/09/28)
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- A chiral double tooth nitrogen phosphine ligand and its asymmetric catalytic reaction in the application of the (by machine translation)
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The invention relates to a nitrogen phosphine double tooth ligand and its asymmetric catalytic reaction in the application. In the present invention discloses a novel double-phosphine - oxazoline ligand is a containing biphenyl shaft not stable structure of the ligand, and the successful application of α - methyl cinnamic acid and its derivatives of the high-efficiency high-selective asymmetric hydrogenation and its similar reaction. The type ligand the synthetic route is simple, low cost, stable in air, to the carbon-carbon double bond of the asymmetric hydrogenation reaction demonstrate the high activity and high selectivity, has wide industrial applications. (by machine translation)
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Paragraph 0067-0068
(2017/08/29)
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- Copper-catalyzed carboxylation of hydroborated disubstituted alkenes and terminal alkynes with cesium fluoride
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A protocol for the hydrocarboxylation of disubstituted alkenes and terminal alkynes providing access to different secondary carboxylic acids and malonic acid derivatives has been developed. This methodology relies on an initial hydroboration using 9-BBN followed by carboxylation with carbon dioxide in the presence of a copper catalyst and the additive, cesium fluoride. Different cyclohexene, styrene, and stilbene derivatives could be utilized, and alkynes could be transformed into their corresponding dicarboxylic acids in good yields. Finally, six different terpenoids were carboxylated using the developed procedure. (Chemical Equation Presented).
- Juhl, Martin,Laursen, Simon L. R.,Huang, Yuxing,Nielsen, Dennis U.,Daasbjerg, Kim,Skrydstrup, Troels
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p. 1392 - 1396
(2017/05/24)
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- Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids
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We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF?) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.
- Yang, Shuang,Che, Wen,Wu, Hui-Ling,Zhu, Shou-Fei,Zhou, Qi-Lin
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p. 1977 - 1980
(2017/03/09)
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- Novel iridium complex of spirophosphine-carboxylic acid, preparation method and application thereof
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The invention relates to an iridium complex of spirophosphine-carboxylic acid, a preparation method and application thereof. The iridium complex of spirophosphine-carboxylic acid is a compound with a structure shown as formula (I), wherein n=0-3; and the values of R1, R2, R3, R4, R5, R6 and R7 are defined as claim 1. Substituted 7-carboxyl-7'-diarylphosphino-1, 1'-spirobiindane is taken as the ligand to from carboxylic acid anion under the action of alkali, and then complexation with an iridium precursor is carried out to obtain different iridium/spirophosphine-carboxylic acid complexes. The iridium complex of spirophosphine-carboxylic acid provided by the invention can catalyze the asymmetric hydrogenation reaction of a variety of unsaturated carboxylic acids, and show high activity and enantioselectivity, thus having good industrialization prospects. (formula (I)).
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Paragraph 0081-0085
(2017/05/20)
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- Direct β-Selective Hydrocarboxylation of Styrenes with CO2 Enabled by Continuous Flow Photoredox Catalysis
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The direct β-selective hydrocarboxylation of styrenes under atmospheric pressure of CO2 has been developed using photoredox catalysis in continuous flow. The scope of this methodology was demonstrated with a range of functionalized terminal styrenes, as well as α-substituted and β-substituted styrenes.
- Seo, Hyowon,Liu, Aofei,Jamison, Timothy F.
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supporting information
p. 13969 - 13972
(2017/10/17)
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- Styrene-acrylic acid synthetic method of the compound
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The invention discloses a method for directly achieving direct arylation reaction of benzene and carbonyl beta-bite sp3C-H bonds employing palladium acetate as a catalyst under the action of bidentate guide base, so as to synthesize a phenylpropionic acid compound. The method comprises the following steps: sequentially adding a 2-propionamido-pyridine-1-oxide, palladium acetate, gibbsite dipotassium phosphate, an aryl iodide compound and dimethylsulfoxide to a shrek tube in an air atmosphere, and reacting for 20-30 hours; after the reaction is ended, cooling to a room temperature, extracting, drying, concentrating and carrying out chromatographic separation to obtain an arylated product; dissolving the obtained arylated product into an ethanol solution of NaOH and reacting for 20-30 hours; and after reaction is ended, neutralizing, extracting, drying, concentrating and carrying out column chromatography to obtain the phenylpropionic acid compound. The method is mild in reaction condition, and good in functional group tolerance; an external additive is not needed; and the carbonyl beta-bite sp3C-H bonds in the 2-propionyl aminopyridine-1-oxide can be directly arylated.
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Paragraph 0030; 0032; 0037; 0038
(2017/05/02)
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- Asymmetric Hydrogenation of α-Substituted Acrylic Acids Catalyzed by a Ruthenocenyl Phosphino-oxazoline-Ruthenium Complex
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Asymmetric hydrogenation of various α-substituted acrylic acids was carried out using RuPHOX-Ru as a chiral catalyst under 5 bar H2, affording the corresponding chiral α-substituted propanic acids in up to 99% yield and 99.9% ee. The reaction could be performed on a gram-scale with a relatively low catalyst loading (up to 5000 S/C), and the resulting product (97%, 99.3% ee) can be used as a key intermediate to construct bioactive chiral molecules. The asymmetric protocol was successfully applied to an asymmetric synthesis of dihydroartemisinic acid, a key intermediate required for the industrial synthesis of the antimalarial drug artemisinin.
- Li, Jing,Shen, Jiefeng,Xia, Chao,Wang, Yanzhao,Liu, Delong,Zhang, Wanbin
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supporting information
p. 2122 - 2125
(2016/06/01)
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- Chiral diphosphine ligand in asymmetric hydrogenation thereof and related application of the catalyst in the reaction (by machine translation)
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The invention discloses a chiral diphosphine ligand based on ferrocene skeleton in asymmetric hydrogenation thereof and related application of the catalyst in the reaction. This kind of novel chiral diphosphine ligand has as the general formula I The structure of the shown, wherein R 1 can be is methyl, phenyl, tert-butyl, hydroxy, etc.. R 2 can be ethyl, phenyl, cyclohexyl, methyl phenyl, tert-butyl, 3,5-dimethyl phenyl, 3,5-di-tert-butyl phenyl, 3,5-di-tert-butyl-4-methoxybenzene, 2,6-dimethoxyphenyl, 2,6-dimethyl phenyl, anthryl. At the same time, two phosphine atom bridged between the can is phenyl, naphthyl, alkyl or the like. At the same time, this invention has disclosed this kind of novel chiral diphosphine ligand synthesis and in preparation of chiral pharmaceutical ibuprofen and a naproxen, and the like. (by machine translation)
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Paragraph 0104; 0108; 0109
(2016/10/09)
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- Synthesis of Enantiomerically Enriched 2-Hydroxymethylalkanoic Acids by Oxidative Desymmetrisation of Achiral 1,3-Diols Mediated by Acetobacter aceti
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The stereoselective desymmetrisation of achiral 2-alkyl-1,3-diols is performed by oxidation of one of the two enantiotopic primary alcohol moieties by means of Acetobacter aceti MIM 2000/28 to afford the corresponding chiral 2-hydroxymethyl alkanoic acids (up to 94 % ee). The procedure, carried out in aqueous medium under mild conditions of pH, temperature and pressure, contributes to enlarge the portfolio of enzymatic oxidations available to organic chemists for the development of sustainable manufacturing processes.
- Brenna, Elisabetta,Cannavale, Flavia,Crotti, Michele,De Vitis, Valerio,Gatti, Francesco G.,Migliazza, Gaia,Molinari, Francesco,Parmeggiani, Fabio,Romano, Diego,Santangelo, Sara
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p. 3796 - 3803
(2016/12/24)
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- Unactivated C(sp3)-H hydroxylation through palladium catalysis with H2O as the oxygen source
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A novel palladium catalyzed hydroxylation of unactivated aliphatic C(sp3)-H bonds was successfully developed. Different from conventional methods, water serves as the hydroxyl group source in the reaction. This new reaction demonstrates good reactivity and broad functional group tolerance. The C-H hydroxylated products can be readily transformed into various highly valuable chemicals via known transformations. Based on experimental and theoretical studies, a mechanism involving the Pd(ii)/(iv) pathway is proposed for this hydroxylation reaction.
- Hu, Jiantao,Lan, Tianlong,Sun, Yihua,Chen, Hui,Yao, Jiannian,Rao, Yu
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supporting information
p. 14929 - 14932
(2015/10/06)
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- Systematic methodology for the development of biocatalytic hydrogen-borrowing cascades: Application to the synthesis of chiral α-substituted carboxylic acids from α-substituted α,β-unsaturated aldehydes
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Ene-reductases (ERs) are flavin dependent enzymes that catalyze the asymmetric reduction of activated carbon-carbon double bonds. In particular, α,β-unsaturated carbonyl compounds (e.g. enals and enones) as well as nitroalkenes are rapidly reduced. Conversely, α,β-unsaturated esters are poorly accepted substrates whereas free carboxylic acids are not converted at all. The only exceptions are α,β-unsaturated diacids, diesters as well as esters bearing an electron-withdrawing group in α- or β-position. Here, we present an alternative approach that has a general applicability for directly obtaining diverse chiral α-substituted carboxylic acids. This approach combines two enzyme classes, namely ERs and aldehyde dehydrogenases (Ald-DHs), in a concurrent reductive-oxidative biocatalytic cascade. This strategy has several advantages as the starting material is an α-substituted α,β-unsaturated aldehyde, a class of compounds extremely reactive for the reduction of the alkene moiety. Furthermore no external hydride source from a sacrificial substrate (e.g. glucose, formate) is required since the hydride for the first reductive step is liberated in the second oxidative step. Such a process is defined as a hydrogen-borrowing cascade. This methodology has wide applicability as it was successfully applied to the synthesis of chiral substituted hydrocinnamic acids, aliphatic acids, heterocycles and even acetylated amino acids with elevated yield, chemo- and stereo-selectivity. A systematic methodology for optimizing the hydrogen-borrowing two-enzyme synthesis of α-chiral substituted carboxylic acids was developed. This systematic methodology has general applicability for the development of diverse hydrogen-borrowing processes that possess the highest atom efficiency and the lowest environmental impact. This journal is
- Knaus, Tanja,Mutti, Francesco G.,Humphreys, Luke D.,Turner, Nicholas J.,Scrutton, Nigel S.
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p. 223 - 233
(2015/02/19)
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- Soluble polymer supported 2-imidazolidinone chiral auxiliary and method for manufacturing the same
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The present invention relates to a chiral auxiliary agent and a manufacturing method thereof and, more specifically, to a 2-imidazolidinone chiral auxiliary agent supported onto a polymer soluble in an organic solvent and a manufacturing method thereof. The chiral auxiliary agent in the present invention shows effects of being easy to separate reaction products and the chiral auxiliary agent after a termination of a reaction while fulfilling an economic efficacy of chiral auxiliary molecules by being supported onto the polymer soluble in the organic solvent.COPYRIGHT KIPO 2015
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Paragraph 0092; 0097-0101
(2017/01/02)
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- Enantioselective hydrogenation of α,β-unsaturated carboxylic acid over cinchonidine-modified Pd nanoparticles confined in carbon nanotubes
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We report the enantioselective hydrogenation of α,β-unsaturated acid catalyzed by Pd nanoparticles in carbon nanotubes (CNTs) taking the advantage of the channels as nanoreactors. The Pd nanocatalyst inside the channels of CNTs shows higher activity and e
- Guan, Zaihong,Lu, Shengmei,Li, Can
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- Metathesis for catalyst design: Metacatalysis
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Prior studies have shown an effective way to produce diverse ligand sets for catalyst discovery is by using mixtures of monodentate forms to generate catalysts in situ. Research described here was performed to illustrate that alkene-functionalized monodentate ligands could be used in this way and in another that increases the diversity of the ligand library in an interesting way. Specifically, we hypothesized that as well as being used as monomers, these alkenes could be cross metathesized in situ immediately before the catalysis step. This combination of metathesis to form ligands in situ, then catalysis is referred to here as metacatalysis. In the event, a library of quinidine and quinine alkaloid-derived phosphites were tested as mixtures of monomers and dimers formed via metathesis in situ. The data obtained illustrated that metacatalysis can be used to identify ligands that positively and negatively modulate enantioselectivities in iridium-mediated hydrogenations of α,β-unsaturated carboxylic acid derivatives, relative to the mixtures of the monomeric forms used.
- Khumsubdee, Sakunchai,Burgess, Kevin
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supporting information
p. 1326 - 1335
(2014/02/14)
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- Influence of the position of the substituent on the efficiency of lipase-mediated resolutions of 3-aryl alkanoic acids
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Hydrolase-catalysed kinetic resolutions to provide enantioenriched α-substituted 3-aryl alkanoic acids are described. (S)-2-Methyl-3- phenylpropanoic acid (S)-1a was prepared in 96% ee by Pseudomonas fluorescens catalysed ester hydrolysis, while, Candida antarctica lipase B (immob) resolved the α-ethyl substituted 3-arylalkanoic acid (R)-1b in 82% ee. The influence of the position of the substituent relative to the ester site on the efficiency and enantioselectivity of the biotransformation is also explored; the same lipases were found to resolve both the α- and β-substituted alkanoic acids. Furthermore, the steric effect of substituents at the C2 stereogenic centre relative to that for their C3 substituted counterparts on the efficiency and stereoselectivity is discussed.
- Deasy, Rebecca E.,Moody, Thomas S.,Maguire, Anita R.
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p. 1480 - 1487
(2013/12/04)
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- Memory of chirality in rebound cyclizations of α-amide radicals
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Reduction of (S)-N-(2-bromoallyl)-N-(tert-butyl)-2-methyl-3- phenylpropanamide with tributyltin hydride provides (3S,4S)-3-benzyl-1-(tert- butyl)-3,4-dimethylpyrrolidin-2-one with about 80% retention of chirality at the stereocenter adjacent to the amide carbonyl group. This memory of chirality is suggested to occur by transfer of chirality from a stereocenter to an axis, then from the axis back to a new stereocenter.
- Sasmal, Aniruddha,Taniguchi, Tsuyoshi,Wipf, Peter,Curran, Dennis P.
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supporting information
p. 1 - 5
(2013/03/13)
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- Synthesis and SAR study of modulators inhibiting tRXRα-dependent AKT activation
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RXRα represents an intriguing and unique target for pharmacologic interventions. We recently showed that Sulindac and a designed analog could bind to RXRα and modulate its biological activity, including inhibition of the interaction of an N-terminally truncated RXRα (tRXRα) with the p85α regulatory subunit of phosphatidylinositol-3-OH kinase (PI3K). Here we report the synthesis, testing and SAR of a series of novel analogs of Sulindac as potential modulators for inhibiting tRXRα-dependent AKT activation. A new compound 30 was identified to have improved biological activity.
- Wang, Zhi-Gang,Chen, Liqun,Chen, Jiebo,Zheng, Jian-Feng,Gao, Weiwei,Zeng, Zhiping,Zhou, Hu,Zhang, Xiao-Kun,Huang, Pei-Qiang,Su, Ying
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p. 632 - 648
(2013/05/09)
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- A comparison between oxazoline-imidazolinylidene, -imidazolylidine, -benzimidazolylidene hydrogenation catalysts
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Imidazolinylidene, imidazolylidine, benzimidazolylidene complexes 1a-c were prepared and tested in asymmetric hydrogenations of a series of largely unfunctionalized alkenes. Similarities and differences in the catalytic performance of these complexes were rationalized in terms of the predicted mechanisms of these reactions, and their relative tendencies to generate protons under the hydrogenation conditions.
- Khumsubdee, Sakunchai,Fan, Yubo,Burgess, Kevin
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supporting information
p. 9969 - 9974
(2013/10/22)
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