244277-48-3Relevant articles and documents
Ru-Catalyzed Chemo- and Enantioselective Hydrogenation of β-Diketones Assisted by the Neighboring Heteroatoms
Li, Wanfang,Lu, Bin,Xie, Xiaomin,Zhang, Zhaoguo
supporting information, p. 5509 - 5513 (2019/08/01)
A highly chemo- and enantioselective hydrogenation of β-diketones was achieved by using [Ru(benzene)(S)-SunPhosCl]Cl for consistency in THF. The neighboring heteroatoms played important roles in guaranteeing the reactivity and controlling the chemoselectivity. These results suggested a potential approach for the clean and facile synthesis of functionalized chiral β-hydroxy ketones, which could otherwise be prepared through much less step-economic transformations.
Asymmetric transfer hydrogenation of γ-aryl α,γ-dioxo-butyric acid esters
Mo, Yuan-Zhao,Nie, Hui-Fang,Lei, Yang,Zhang, Dong-Xu,Li, Xiao-Ye,Zhang, Sheng-Yong,Wang, Qiao-Feng
, p. 33126 - 33131 (2016/05/09)
The asymmetric transfer hydrogenation (ATH) of a series of γ-aryl-α,γ-dioxo-butyric acid esters has been accomplished smoothly. Six ferrocene-based chiral ligands have been prepared and applied in the reactions respectively. Simultaneously, enantiopure Ts
Bronsted acid catalyzed asymmetric aldol reaction: A complementary approach to enamine catalysis
Pousse, Guillaume,Cavelier, Fabien Le,Humphreys, Luke,Rouden, Jacques,Blanchet, Jerome
supporting information; experimental part, p. 3582 - 3585 (2010/11/05)
A syn-enantioselective aldol reaction has been developed using Bronsted acid catalysis based on H8-BINOL-derived phosphoric acids. This method affords an efficient synthesis of various β-hydroxy ketones, some of which could not be synthesized u
Chemoenzymatic synthesis of α-Hydroxy-β-methyl-γ-hydroxy esters: Role of the keto-enol equilibrium to control the stereoselective hydrogenation in a key step
Milagre, Cintia D. F.,Milagre, Humberto M. S.,Moran, Paula J. S.,Rodrigues, J. Augusto R.
experimental part, p. 1410 - 1418 (2010/05/19)
"Chemical Equation Presented" α-Hydroxy-β-methyl- γ-hydroxy esters not only are found in many natural products and potent drugs but also are useful intermediates in organic synthesis due to their highly functionalized skeleton that can be further manipula
Chemo-enzymatic synthesis of ethyl (R)-2-hydroxy-4-phenylbutyrate
D'Arrigo, Paola,Pedrocchi-Fantoni, Giuseppe,Servi, Stefano
experimental part, p. 914 - 918 (2010/08/19)
A new biocatalytic strategy to obtain the ethyl (R)-2-hydroxy-4-oxo-4- phenylbutyrate precursor of ethyl (R)-2-hydroxy-4-phenylbutyrate, an important intermediate in the synthesis of a variety of ACE inhibitors, has been set up. Starting from ethyl 2,4-dioxo-4-phenylbutyrate, a screen of microorganisms has been performed in order to find the best catalyst able to reduce the keto group in the α-position with high chemo- and enantioselectivity. The biotransformation catalyzed by Pichia pastoris CBS 704 gave the best results in terms of conversion and enantioselectivity. The addition of adsorbing resins in the fermentation medium is effective in controlling substrate and product concentration in the medium, thus improving both conversion and enantioselectivity of the biotransformation. Preliminary experiments in a continuous batch reactor with growing culture of P. pastoris will be also presented.
Lipase activity of Lecitase Ultra: characterization and applications in enantioselective reactions
Mishra, Mithilesh Kumar,Kumaraguru, Thenkrishnan,Sheelu, Gurrala,Fadnavis, Nitin W.
experimental part, p. 2854 - 2860 (2010/04/05)
The general properties of Lecitase Ultra, a phospholipase manufactured and marketed by Novozymes, Denmark, have been studied after purification by ultrafiltration. The enzyme has a molecular mass of 35 KD, pH-optimum of 8.5, and appears to possess a single active site which exhibits both the lipase and phospholipase activities that increase in the presence of Ca2+ and Mg2+ ions. The enzyme is inhibited by heavy metal ions and surfactants, and does not accept p-nitrophenyl acetate and glycerol triacetate. Substrates, such as glycerol tributyrate and p-nitrophenyl palmitate, esters of N-acetyl-α-amino acids and α-hydroxy acids are readily accepted. Amino acids with aliphatic residues, such as alanine, isoleucine, and methionine, are hydrolyzed with high enantioselectivity for the l-enantiomer (E >100), but amino acids with aromatic residues such as phenylalanine and phenylglycine, and esters of α-hydroxy acids are hydrolyzed with low enantioselectivity (E = 1-5). Immobilization of the enzyme in a gelatin matrix (gelozyme) leads to a marginal improvement in the enantioselectivity for these substrates. However, a dramatic improvement in enantioselectivity is observed for ethyl 2-hydroxy-4-oxo-4-phenylbutyrate (E value increases from 4.5 to 19.5 with S-selectivity). Similarly, glycidate esters, such as ethyl trans-(±)-3-phenyl glycidate and methyl trans-(±)-3-(4-methoxyphenyl) glycidate, are selectively hydrolyzed with a remarkable selectivity towards the (2S,3R)-enantiomer providing unreacted (2R,3S)-glycidate esters (ee >99%, conversion 52-55%) by the immobilized enzyme.
Enantioselective activation of aldehydes by chiral phosphoric acid catalysts in an aza-ene-type reaction between glyoxylate and enecarbamate
Terada, Masahiro,Soga, Kazuyo,Momiyama, Norie
supporting information; experimental part, p. 4122 - 4125 (2009/03/12)
(Chemical Equation Presented) Double interaction doesit: Highly enantio- and diastereoselective aza-ene-type reaction of glyoxylate with an enecarbamate is accomplished by using a binol-derived phosphoric acid catalyst (see scheme). DFT computational analysis revealed that two hydrogen bonds formed between the catalyst and the aldehyde are critical for the high enantioselectivity.
Highly enantioselective carbonyl-ene reactions catalyzed by a hindered silyl-salen-cobalt complex
Hutson, Gerri E.,Dave, Apurva H.,Rawal, Viresh H.
, p. 3869 - 3872 (2008/02/11)
We report here the enantioselective carbonyl-ene reactions of various 1,1-disubstituted and trisubstituted alkenes with ethyl glyoxylate. The reactions are catalyzed by a new Co-salen complex, in which bulky triisobutylsilyl (TIBS) substituents occupy the
Enantio- and regiospecific reduction of ethyl 4-phenyl-2,4-dioxobutyrate with baker's yeast: Preparation of (R)-HPB ester
Fadnavis, Nitin W.,Radhika, Kasiraman R.
, p. 3443 - 3447 (2007/10/03)
Ethyl 2,4-dioxo-4-phenylbutyrate obtained by condensation of acetophenone with diethyl oxalate is reduced enantio- and regiospecifically by baker's yeast in a diisopropyl ether/water two-phase system to give (-)-ethyl (R)-2-hydroxy-4-oxo-4-phenylbutyrate with an ee = 98% in 80% isolated yield. The hydroxyester was hydrogenated over Pd-C to obtain (-)-ethyl (R)-2-hydroxy-4-phenylbutyrate (HPB ester), an important intermediate for the synthesis of ACE inhibitors. Prolonged contact of the reduction product with baker's yeast produced 3-phenyl 3-oxo propanol in 90% yield.
Ethyl 2,4-dioxo-4-phenylbutyrate: A versatile intermediate for the large-scale preparation of enantiomerically pure α-hydroxy and α-amino acid esters
Blaser, Hans-Ulrich,Burkhardt, Stephan,Kirner, Hans Juerg,Moessner, Tanja,Studer, Martin
, p. 1679 - 1682 (2007/10/03)
Starting from ethyl 2,4-dioxo-4-phenylbutyrate, both enantiomers of six enantiomerically pure α-hydroxy and α-amino acid esters (homophenylalanine derivatives) were prepared on >100 g scale. The key step involves a Pt-cinchona catalyzed enantioselective hydrogenation followed by enrichment via crystallization. All derivatives are commercially available.
