- Direct Aerobic α-Hydroxylation of Arylacetates for the Synthesis of Mandelates
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Aerobic α-hydroxylation of α-methylene esters has proven challenging due to overoxidation and hydrolysis of the materials. In this article, KOtBu-promoted TBAB-catalyzed α-hydroxylation of α-methylene aryl esters using O2as the oxyge
- Xu, Changming,Li, Xiangfan,Bai, Lei
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p. 4298 - 4304
(2022/03/16)
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- Cobalt-Catalyzed Transfer Hydrogenation of α-Ketoesters and N-Cyclicsulfonylimides Using H2O as Hydrogen Source
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A Co-catalyzed effective transfer hydrogenation of various α-ketoesters and N-cyclicsulfonylimides by safe and environmentally benign H2O as hydrogen source is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N-cyclicsulfonylimides. (Figure presented.).
- Gao, Yang,Zhang, Xuexin,Laishram, Ronibala Devi,Chen, Jingchao,Li, Kangkui,Zhang, Keyang,Zeng, Guangzhi,Fan, Baomin
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p. 3991 - 3997
(2019/08/02)
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- New 4-aryl-1,3,2-oxathiazolylium-5-olates: Chemical synthesis and photochemical stability of a novel series of S-nitrosothiols
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S-nitrosothiols (RSNOs) remain one of the most popular classes of NO-donating compounds due to their ability to release nitric oxide (NO) under non-enzymatic means whilst producing an inert disulphide by-product. However, alligning these compounds to the different biological fields of NO research has proved to be problematic due to the inherent instability of such compounds under a variety of conditions including heat, light and the presence of copper ions. 1,3,2-Oxathiazolylium-5-olates (OZOs) represent an interesting subclass of S-nitrosothiols that lock the –SNO moiety into a five membered heterocyclic ring in an attempt to improve the compound's overall stability. The synthesis of a novel series of halogen-containing OZOs was comprehensively studied resulting in a seven-step route and overall yields ranging between 21 and 37%. The photochemical stability of these compounds was assessed to determine if S-nitrosothiols locked within these mesoionic ring systems can offer greater stability and thereby release NO in a more controllable fashion than their non-cyclic counterparts.
- Eilertsen, Monica,Allin, Steve M.,Pearson, Russell J.
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supporting information
p. 1106 - 1110
(2018/02/28)
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- A containing "1, 3, 4 - oxadiazole thioether" mandelic acid derivatives and use thereof
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The invention discloses a containing "1, 3, 4 - oxadiazole thioether" mandelic acid derivatives and their use in the application of the fungi anti-plants sickness, the compound has the general formula (B) structure shown: In the formula, R1 Is H, methyl, fluorine or chlorine, R2 C for containing1 - 3 Straight-chain alkyl, containing C1 - 4 Branched alkyl, propenyl, propynyl or mono-substituted benzyl, wherein the single substituted benzyl substituent is "nitro, methyl, trifluoromethyl, methoxy, three methoxy, fluorine, and bromine". The invention to replace the mandelic acid as the skeleton, mandelic acid introduced in the structure of the "oxadiazole thioether" structure, design synthesizing a containing "1, 3, 4 - oxadiazole thioether" structure of the mandelic acid derivatives, anti-plant disease fungal activity tests show that the class of compounds of plant diseases caused by fungi has good inhibition activity, for the new pesticide research and development and create provide important scientific basis.
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Paragraph 0051-0054
(2019/01/06)
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- The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
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A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
- Guo, Huan,Li, Jing,Liu, Delong,Zhang, Wanbin
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p. 3665 - 3673
(2017/09/11)
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- Ru-MACHO-Catalyzed Highly Chemoselective Hydrogenation of α-Keto Esters to 1,2-Diols or α-Hydroxy Esters
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A ruthenium pincer catalyst has been shown to be highly effective for the hydrogenation of a wide range of α-keto esters, affording either diols or hydroxy esters depending on the choice of reaction conditions. Strong base, high temperature, and pressure favor the formation of diols whilst the opposite is true for the hydroxy esters.
- Gao, Shaochan,Tang, Weijun,Zhang, Minghui,Wang, Chao,Xiao, Jianliang
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supporting information
p. 1748 - 1752
(2016/07/06)
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- Dual pathway for the asymmetric transfer hydrogenation of α-ketoimides to chiral α-hydroxy imides or chiral α-hydroxy esters
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In an enantioselective reaction, we expect to obtain two types of chiral products through a controllable strategy in asymmetric catalysis. Herein, we develop Ru-catalysed asymmetric transfer hydrogenation of α-ketoimides to realise an enantioselective construction of chiral α-hydroxy imides or chiral α-hydroxy esters. The transformation of α-ketoimides catalysed by (S,S)-[RuCl(η6-mesitylene)diamine] can afford various chiral α-hydroxy imides with high yields and enantioselectivities, whereas that catalysed by (S,S)-[RuCl(η6-hexamethylbenzene)diamine] gives the desirable chiral α-hydroxy esters through a slight adjustment of the reaction conditions. The method described here is a controllable organic transformation with sodium formate as a hydrogen source under mild reaction conditions, and the benefit of this transformation is that various chiral α-hydroxy imides or α-hydroxy esters can be obtained selectively from α-ketoimides. Selective directive: An enantioselective transformation in the Ru-catalyzed asymmetric transfer hydrogenation of α-ketoimides to chiral α-hydroxy imides or α-hydroxy esters is developed. The transformation of α-ketoimides catalyzed by (S,S)-[RuCl(η6-mesitylene)diamine] can afford various chiral α-hydroxy imides with high yields and enantioselectivities, whereas that catalyzed by (S,S)-[RuCl(η6-hexamethylbenzene)diamine] give desirable chiral α-hydroxy esters through a slight adjustment of reaction conditions.
- Zhao, Qiankun,Zhao, Yuxi,Liao, Hang,Cheng, Tanyu,Liu, Guohua
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p. 412 - 416
(2016/02/05)
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- Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
- Chen, Peiran,Yang, Wenhong
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supporting information
p. 2290 - 2294
(2014/04/17)
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- Carboxylation with CO2 via brook rearrangement: Preparation of α-hydroxy acid derivatives
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In the presence of CsF, a wide range of α-substituted α-siloxy silanes were carboxylated under a CO2 atmosphere (1 atm) via Brook rearrangement. A variety of α-substituents including aryl, alkenyl, and alkyl groups were tolerated to afford α-hydroxy acids in moderate-to-high yields. One-pot synthesis from aldehydes using PhMe2SiLi and CO 2 was also possible, providing α-hydroxy acids without the isolation of an α-hydroxy silane.
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
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- 1,3-Bis(2,4,6-trimethylphenyl)imidazolium chloride in combination with triethylamine: An improved catalytic system for hydroacylation/reduction of activated ketones
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A rapid, economic, and high yielding methodology has been developed for hydroacylation/reduction of activated ketones by using 1,3-bis(2,4,6- trimethylphenyl)imidazolium chloride as a catalyst in combination with triethylamine. The reaction proceeded at an ambient temperature via generating N-heterocyclic carbene in situ that interacted with the (hetero)aryl aldehyde employed. While the reduction of ketones takes place in MeOH, the hydroacylation process was found to be effective in THF for both electron rich and deficient aldehydes.
- Sreenivasulu,Arun Kumar,Sateesh Reddy,Siva Kumar,Rajender Kumar,Chandrasekhar,Pal, Manojit
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supporting information; experimental part
p. 727 - 732
(2011/03/21)
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- Matching and mismatching effects of hybrid chiral biaxial bisphosphine ligands in enantioselective hydrogenation of ketoesters
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A study was conducted to demonstrate matching and mismatching of hybrid chiral biaxial bisphosphine ligands in enantioselective hydrogenation of ketoesters. A novel class of conformationally rigid Cn-TunePhos was developed by introducing a bridge with variable length to link the chiral atropisometic biaryl groups. The conformationally rigid Cn-TunePhos was introduce to investigate the synthesis and use of new chiral biophosphine ligands in asymmetric catalysis. A strategy was introduced for the synthesis of a pair of diastereoisomeric forms of ligands 1, 2, and an analogous ligand 3 to assess the effects of stereochemical matching and mismatching interactions upon the structural and catalytic properties of the corresponding ruthenium complexes. Their applications in highly efficient Ru-catalyzed asymmetric hydrogenation for the enantioselective synthesis of α- and β-hydroxy acid derivatives were also explored.
- Sun, Xianfeng,Li, Wei,Zhou, Le,Zhang, Xumu
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supporting information; scheme or table
p. 7302 - 7305
(2010/03/24)
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- PROCESS FOR THE PREPARATION OF FLUOROPHENYLACETIC ACIDS AND DERIVATIVES THEREOF
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The object of the present invention is a process for the preparation of fluorophenylacetic acids and derivatives thereof, particularly of 2,4, 5-trifluorophenylacetic acid, starting from the corresponding mandelic acids.
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Page/Page column 20-21
(2008/12/06)
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- Catalytic asymmetric reaction with water: Enantioselective synthesis of α-hydroxyesters by a copper-carbenoid O-H insertion reaction
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(Chemical Equation Presented) Taking on water: A novel catalytic asymmetric metal-carbenoid insertion reaction with water has been developed with copper complexes of chiral spiro bisoxazoline ligands as catalysts. This reaction provides an efficient and practical procedure for preparing chiral α-hydroxyesters and acids starting from readily available materials in high yields and enantioselectivities. BArF- = [B{3,5-(CF3)2C6H3)} 4]-.
- Zhu, Shou-Fei,Chen, Chao,Cai, Yan,Zhou, Qi-Lin
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p. 932 - 934
(2008/09/20)
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- Convenient divergent strategy for the synthesis of TunePhos-type chiral diphosphine ligands and their applications in highly enantioselective Ru-catalyzed hydrogenations
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(Chemical Equation Presented) A convenient, divergent strategy for the synthesis of a series of modular and fine-tunable C3-TunePhos-type chiral diphosphine ligands and their applications in highly efficient Rucatalyzed asymmetric hydrogenations were explored. Up to 97 and 99% ee values were achieved for the enantioselective synthesis of β-methyl chiral amines and α-hydroxy acid derivatives, respectively.
- Sun, Xianfeng,Zhou, Le,Li, Wei,Zhang, Xumu
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p. 1143 - 1146
(2008/09/18)
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- Rational design of 6-(2,4-diaminopyrimidinyl)-1,4-benzoxazin-3-ones as small molecule renin inhibitors
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We report the design and synthesis of a series of 6-(2,4-diaminopyrimidinyl)-1,4-benzoxazin-3-ones as orally bioavailable small molecule inhibitors of renin. Compounds with a 2-methyl-2-aryl substitution pattern exhibit potent renin inhibition and good pe
- Powell, Noel A.,Ciske, Fred L.,Cai, Cuiman,Holsworth, Daniel D.,Mennen, Ken,Van Huis, Chad A.,Jalaie, Mehran,Day, Jacqueline,Mastronardi, Michelle,McConnell, Pat,Mochalkin, Igor,Zhang, Erli,Ryan, Michael J.,Bryant, John,Collard, Wendy,Ferreira, Suzie,Gu, Chungang,Collins, Roxane,Edmunds, Jeremy J.
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p. 5912 - 5949
(2008/03/18)
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- Highly enantioselective hydrogenation of α-keto esters catalyzed by Ru-tunephos complexes
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Various enantiomerically pure α-hydroxy esters were synthesized by asymmetric hydrogenation of α-keto esters catalyzed by Ru-C n-Tunephos complex. Up to 97.1% ee has been achieved for both α-aryl and α-alkyl substituted α-keto esters. Georg Thieme Verlag Stuttgart.
- Wang, Chun-Jiang,Sun, Xianfeng,Zhang, Xumu
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p. 1169 - 1172
(2007/10/03)
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- Oxadiazole benzenesulfonamides as selective beta 3 Agonist for the treatment of Diabetes and Obesity
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Oxadiazole substituted benzenesulfonamides are selective beta 3 adrenergic receptor agonists with very little beta 1 and beta 2 adrenergic receptor activity and as such the compounds are capable of increasing lipolysis and energy expenditure in cells. The
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- Resolution of Mandelic Acids by Lipase-catalysed Transesterifications in Organic Media: Inversion of Enantioselectivity mediated by the Acyl Donor
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The lipase-catalysed highly enantioselective deacylation and acylation of mandelic acid derivatives and the inversion of enantioselectivity mediated by the acyl donor are described.
- Miyazawa, Toshifumi,Kurita, Sota,Ueji, Shinichi,Yamada, Takashi,Kuwata, Shigeru
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p. 2253 - 2258
(2007/10/02)
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- Enantioselectivity of carbonic anhydrase catalyzed hydrolysis of mandelic methyl esters
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We report the first enantioselective hydrolysis of esters catalyzed by caebonic anhydrase.We found that mandelic methyl esters are good substrates for carbonic anhydrase.The R enantiomers are better substrates and enantiomeric excess values are moderate (40-51percent).
- Chenevert, Robert,Letourneau, Martin
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p. 314 - 316
(2007/10/02)
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