20698-91-3Relevant articles and documents
Effects of organic solvents and ionic liquids on the aminolysis of (RS)-methyl mandelate catalyzed by lipases
Pilissao, Cristiane,Nascimento, Maria Da Graca
, p. 428 - 433 (2006)
The enzymatic resolution of (RS)-methyl mandelate with n-butylamine using lipases in organic solvents (n-hexane, tert-butanol, and chloroform) and ionic liquids [BMIm][BF4] and [BMIm][PF6] is reported. The amide configuration is dependent on the organic solvent. When using mixtures of chloroform or tert-butanol/ionic liquids (10:1 v/v) with CAL-B as the catalyst, the amides were obtained in high enantiomeric excess (eep >99% and E >200).
New data to the origin of rate enhancement on the Pt-cinchona catalyzed enantioselective hydrogenation of activated ketones using continuous-flow fixed-bed reactor system
Szoellosi, Gyoergy,Cserenyi, Szabolcs,Fueloep, Ferenc,Bartok, Mihaly
, p. 245 - 253 (2008)
A study on the origin of rate enhancement (RE) in the enantioselective heterogeneous catalytic hydrogenation of methyl benzoylformate (MBF), ketopantolactone (KPL) and pyruvic aldehyde dimethyl acetal (PA) under the Orito reaction conditions over Pt catalyst modified with parent cinchona alkaloids, as compared to the unmodified catalyst is presented. The hydrogenations were carried out in continuous-flow fixed-bed reactor system over 20-100 mg Pt/Al2O3 catalyst in 1 mL min-1 flow of toluene/acetic acid 9/1 solvent mixture under 40-80 bar H2 pressure, at 283 or 293 K using 0.044-2 mM modifier concentration and 45 mM substrate concentration. Our results obtained using racemic hydrogenations followed by three changes of the chiral modifier (on the same catalyst) supported the so-called "ligand acceleration" phenomenon in the enantioselective hydrogenation of activated ketones such as MBF, KPL and PA. In our opinion, RE produced by the first modifier added after racemic hydrogenation can also be explained by the purifying effect of the cinchona. REs observed following further exchanges of modifiers are indicative of the intrinsic character of the phenomenon. This research suggested that the origin of enantiodifferentiation and rate enhancement is the same, namely, both may be traced back-probably in different ways-to the role of the intermediate complexes of the hydrogenation, to its formation and transformation, which in turn depends on numerous factors.
Enantiocomplementary preparation of (S)- and (R)-mandelic acid derivatives via α-hydroxylation of 2-arylacetic acid derivatives and reduction of α-ketoester using microbial whole cells
Chen, Yongzheng,Xu, Jinggang,Xu, Xiaoying,Xia, Yu,Lin, Hui,Xia, Shiwen,Wang, Lixin
, p. 2537 - 2540 (2007)
Forty one microorganisms belonging to different taxonomical groups were used to carry out the enantioselective reduction of methyl benzoylformate to afford the corresponding (R)-methyl mandelate, with moderate to high ee. In contrast, the monooxygenase en
Effect of the neighbouring oxygenated substituent on asymmetric reduction with Hantzsch-type 1,4-dihydropyridines having a chiral sulfinyl group
Miyashita, Kazuyuki,Nishimoto, Masahiro,Murafuji, Hidenobu,Murakami, Asuka,Obika, Satoshi,In, Yasuko,Ishida, Toshimasa,Imanishi, Takeshi
, p. 2535 - 2536 (1996)
Introduction of the oxygen substituent at C-6 of the Hantzsch-type compound having a sulfinyl group at C-5 affects the reduction of ketones with respect to both reactivity and stereoselectivity.
Asymmetric reduction of α-keto esters with Thermus thermophilus NADH-dependent carbonyl reductase using glucose dehydrogenase and alcohol dehydrogenase for cofactor regeneration
Pennacchio, Angela,Giordano, Assunta,Rossi, Mose,Raia, Carlo A.
, p. 4361 - 4366 (2011)
The enantioselective synthesis of methyl (R)-mandelate and methyl (R)-o-chloromandelate was investigated using an NADH-dependent carbonyl reductase from Thermus thermophilus (TtADH) and, separately, archaeal glucose dehydrogenase and Bacillus stearothermo
Substrate-controlled adsorption of cinchonidine during enantioselective hydrogenation on platinum
Schmidt, Erik,Mallat, Tamas,Baiker, Alfons
, p. 140 - 150 (2010)
It is commonly accepted that the origin of enantioselection on chirally modified metals is the control of the adsorption and reactivity of the substrate by the chiral environment of the modifier. Here, we provide the first experimental evidence to a mutual process, namely, that the substrate controls the adsorption and reactivity of cinchonidine (CD) on the metal surface. Our approach is to follow the competing hydrogenation of the quinoline ring, the anchoring moiety of CD, in the presence or absence of an activated ketone substrate. On Pt/Al2O3 in the weakly interacting solvent toluene, CD (and 10,11-dihydro-CD) favors a C(4′) - pro(S) adsorption geometry and saturation of the heteroaromatic ring gives 1′,2′, 3′,4′(S),10,11-hexahydro-CD {(S)-CDH6} in excess. Addition of methyl benzoylformate, ketopantolactone, or ethyl pyruvate inverts the dominant conformation of CD to C(4′) - pro(R) as indicated by the major product (R)-CDH6, and even the rate is higher by about 30% ("inverse ligand acceleration"). Acetic acid that interacts strongly with CD exerts a similar effect on quinoline hydrogenation. In contrast, the product α-hydroxyester interacts weakly with CD, decelerates the hydrogenation of the quinoline ring and the de of CDH6 depends on the chirality of the α-hydroxyester. These unexpected observations provide a fundamentally new insight into the complexity of the surface conformation of CD and the origin of high enantioselectivity on cinchona-modified Pt.
Kinetic resolutions of racemic amines and alcohols catalyzed by an industrial glutaryl-7-aminocephalosporanic acid acylase with unexpected broad substrate specificity
Raimondi, Stefano,Forti, Luca,Monti, Daniela,Riva, Sergio
, p. 1091 - 1094 (2003)
An industrial glutaryl-7-aminocephalosporanic acid acylase (GAR) possesses a significant broad substrate specificity that crosses over the usual cephalosporanic skeleton. Enantioselective amidase and even esterase activities have been observed with all the glutarates of racemic substrates investigated, with a stereopreference for the (S)-enantiomer. The different physical-chemical properties of reagents and products allow their easy separation by solvent extraction, avoiding cumbersome chromatography or distillation processes during reaction work-up.
Rational design of novel axially chiral NADH models based on configurational control of atropisomeric lactams
Vasse, Jean-Luc,Dupas, Georges,Duflos, Jack,Quéguiner, Guy,Bourguignon, Jean,Levacher, Vincent
, p. 3713 - 3716 (2001)
The preparation of a new class of axially chiral NADH models based on configurational control of atropisomeric lactams is described. The configurational control of this chiral axis is achieved via the presence of a second chirality element installed on th
Homochiral NADH models in the pyrrolo[2,3-b]pyridine series bearing one or two chiral auxiliaries. Asymmetric reduction of methyl benzoylformate and N-acetyl-enamines. Influence of the magnesium salt concentration on the asymmetric induction of reductions
Leroy, Corine,Levacher, Vincent,Dupas, Georges,Queguiner, Guy,Bourguignon, Jean
, p. 3309 - 3318 (1997)
The synthesis of NADH models in the pyrrolo[2,3-b]pyridine series bearing one or two chiral auxiliaries either at the pyridine or at the pyrrole ring is described. These models were involved in the reduction of methyl benzoylformate. The reactivity of the
Cationic complexes with chiral diamine or dithiourea ligands as catalysts for molecular asymmetric hydrogenation
Tommasino, M. Lorraine,Thomazeau, Cecile,Touchard, Francois,Lemaire
, p. 1813 - 1819 (1999)
The asymmetric reduction of phenylglyoxylate methyl ester with molecular hydrogen and catalytic amounts of cationic chiral diamine and dithiourea complexes of rhodium and iridium is reported. The catalytic activity of the complexes is rather different if
Asymmetric Reductions catalysed by Chiral Shift Reagents
Zehani, Sadek,Gelbard, Georges
, p. 1162 - 1163 (1985)
The reduction of methyl phenylglyoxylate to give optically active methyl mandelate by NADH models is catalysed by chiral shift reagents used as Lewis acids.
Highly enantioselective and efficient synthesis of methyl (R)-o-chloromandelate with recombinant E. coli: Toward practical and green access to clopidogrel
Ema, Tadashi,Okita, Nobuyasu,Ide, Sayaka,Sakai, Takashi
, p. 1175 - 1176 (2007)
Methyl (R)-o-chloromandelate ((R)-1), which is an intermediate for a platelet aggregation inhibitor named clopidogrel, was obtained in >99% ee by the asymmetric reduction of methyl o-chlorobenzoylformate (2) (up to 1.0 M) with recombinant E. coli overprod
Atropoisomeric quinolinium salt promoting the access to both enantiomeric forms of methyl mandelate: a versatile NADH mimic.
Vasse, Jean-Luc,Levacher, Vincent,Bourguignon, Jean,Dupas, Georges
, p. 2256 - 2257 (2002)
Asymmetric reduction of methyl benzoylformate by a new NADH mimic is reported; depending on the hydride source used to reduce the NAD+ precursor, NADH mimics so obtained lead to an inversion of enantioselectivity, affording either (R)-methyl mandelate in
A Novel Coenzyme NAD(P)+ - NAD(P)H Model with Axial Chirality. Its Preparation and Stereoselectivity.
Fujii, Masayuki,Kamata, Tohru,Okamura, Mutsuo,Ohno, Atsuyoshi
, p. 905 - 906 (1992)
An axially chiral NAD(P)H model 1 bearing a 2'-methoxy-1'-naphthyl group at the C-2 position is prepared; the reduction of methyl benzoylformate with the optically active model, (+)- or (-)-1, in the presence of magnesium ion gives (R)- or (S)-isomer of m
Catalytic, asymmetric inverse electron demand hetero diels-alder reactions of o-benzoquinone derivatives and ketene enolates
Paull, Daniel H.,Wolfer, Jamison,Grebinski, James W.,Weatherwax, Anthony,Lectka, Thomas
, p. 240 - 246 (2007)
We present an array of [4+2] cycloaddition reactions between ketene enolates, catalytically derived from acid chlorides and cinchona alkaloid nucleophilic catalysts in the presence of stoichiometric base, and o-benzoquinone derivatives. These cycloadditio
Construction of homochiral alkaline-lanthanide heteronuclear helicates with Na+-selective bonding in the self-assembly process
Li, Ge,Wang, Li,Han, Qingxin,Liu, Weisheng
, p. 14595 - 14599 (2019)
A supramolecular approach to distinguish Na+ from other biologically important metal ions was demonstrated. By designing ligands reasonably, Na+-selective bonding was achieved in the construction of homochiral alkaline-lanthanide het
N-methyl-(R)-3-(tert-butyl)-sulfinyl-1,4-dihydropyridine: A novel NADH model compound
Xie, Kun,Liu, You-Cheng,Cui, Yi,Wang, Jian-Ge,Fu, Yao,Mak, Thomas C. W.
, p. 415 - 422 (2007)
We have synthesized a novel chiral NADH model compound, N-methyl-(R)-3-(tert-butyl)-sulphinyl-1,4-dihydropyridine with high enantioselectivity and used it in the reduction of methyl benzoylformate, producing (S)-methyl mandelate in 95% ee. The absolute st
Biocatalysed reductions of α-ketoesters employing CyreneTM as cosolvent
de Gonzalo, Gonzalo
, (2021/02/26)
The search for novel reaction media with environmental friendly properties is an area of great interest in enzyme catalysis. Water is the medium of biocatalysed processes, but due to its properties, sometimes the presence of organic (co)solvents is required. CyreneTM represents one of the newest approaches to this medium engineering. This polar solvent has been employed for the first time in biocatalysed reductions employing purified alcohol dehydrogenases. A set of α-ketoesters has been reduced to the corresponding chiral α-hydroxyesters with high conversions and optical purities, being possible to obtain good results at Cyrene contents of 30% v/v and working at substrate concentrations of 1.0 M in presence of 2.5% v/v of this solvent. At this concentration, the presence of Cyrene has a beneficial effect in the bioreduction conversion.
Redox-driven deracemization of secondary alcohols by sequential ether/O2-mediated oxidation and Ru-catalyzed asymmetric reduction
Yang, Bing,Cui, Peng,Chen, Yongsheng,Liu, Qixing,Zhou, Haifeng
, (2020/10/14)
The deracemization of benzylic alcohols has been achieved using a redox-driven one-pot two-step process. The racemic alcohols were oxidized by bis(methoxypropyl) ether and oxygen to give the ketone intermediates, followed by an asymmetric transfer hydrogenation with a chiral ruthenium catalyst. This compatible oxidation/reduction process gave the enantiomerically enriched alcohols with up to 95% ee values.
