- Base-induced Sommelet–Hauser rearrangement of N-(α-(2-oxyethyl)branched)benzylic glycine ester-derived ammonium salts via a chelated intermediate
-
The base-induced Sommelet–Hauser (S–H) rearrangement of N-(α-branched)benzylic glycine ester-derived ammonium salts 1 was investigated. When the α-branched substituent was a simple alkyl, such as a methyl or butyl, desired S–H rearrangement product 2 was obtained in low yield with formation of the [1,2] Stevens rearranged 4 and Hofmann eliminated products 5 and 6. However, when the α-branched substituent had a 2-oxy moiety, such as 2-acetoxyethyl or 2-benzoyloxyethyl, the yields of 2 were improved. These results could be explained by formation of chelated intermediate C that stabilizes the carbanionic ylide, and the subsequent initial dearomative [2,3] sigmatropic rearrangement would be accelerated. The existence of C was supported by mechanistic experiments. This enhancement effect is not very strong or effective; however, it will expand the synthetic usefulness of ammonium ylide rearrangements.
- Baba, Souya,Hirano, Kazuki,Tayama, Eiji
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supporting information
(2020/03/13)
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- Substrate-controlled Diastereoselective Michael Addition of Alkylidene Malonates by Grignard Reagents
-
Herein is described a diastereoselective Michael addition of Grignard reagents to a, b- unsaturated diethyl malonates incorporated with a 2-oxazolidone chiral auxiliary. The catalyst-free Michael addition proceeds with good chemical efficiency and excellent stereoselectivity; and it provides new thoughts to the asymmetric synthesis of b-substituted b3 amino acid derivatives. Optically active b-amino acid derivatives are commonly found in various biologically active compounds from natural sources and organic synthesis.1, 2 They have been also widely adopted as building blocks for the construction of a/b-peptide foldamers which can mimic biological function of natural a-peptide of enzymes, and are less susceptible to protease degradation than the latter ones.3-7 Therefore, the development of synthetic procedures to prepare b-amino acids is a relevant endeavor. The synthesis of b-amino acids in enantiomerically pure forms continues to attract interest.8-14 The chirality conformation of b-amino acids is generally originated from chiral starting materials, chiral auxiliaries or chiral catalysts. Many approaches were developed for the preparation of substituted b-amino acids, such as hydrogenation of enamines catalyzed by rhodium or palladium with chiral phosphepine ligands15, 16, addition of aromatic amines to a-b unsaturated imides catalyzed by palladium complex17, thiourea catalyzed asymmetric Mannich reaction18 and chiral amine catalysed aza-Michael addition19-22. Although various methods for the synthesis of substituted b-amino acids have been developed with good yield and stereoselectivity, arduous availability of chiral catalysts is still an unavoidable obstacle for the wide use of these methods. Thus, it is still desirable to develop novel catalyst-free strategies to construct these privileged skeletons. The use of chiral auxiliaries is another important strategy to synthesize of b-amino acids. In this context, Goodman et al. reported pseudoephedrine as a chiral auxiliary for the synthesis of a-substituted b-amino acids23. Juaristi et al. accomplished diastereoselective synthesis of b-amino acids using hexahydrobenzoxazolidinones3. These methods provided practical approaches for the synthesis of a-substituted b-amino acids (b2-amino acids). But for b-substituted b-amino acids (b3-amino acids), it is still challenging.
- Zhou, Wei,Xiao, Qingwei,Chang, Yuanyuan,Liu, Qifa,Zang, Xiaohao,Hu, Mengmeng,Zeng, Xi,Du, Zhiyun,Zhong, Guifa
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p. 116 - 121
(2019/12/14)
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- Glutamate as an Efficient Amine Donor for the Synthesis of Chiral β- and γ-Amino Acids Using Transaminase
-
A recyclable glutamate amine donor system employing transaminase (TA), glutamate dehydrogenase (GluDH) and mutant formate dehydrogenase (FDHm) was developed, wherein amine donor Glu was regenerated using GluDH and thereby circumvented the inhibition of TA by α-ketoglutarate. Various enantiopure β-, γ-amino acids, and amines were successfully synthesized with high conversions and excellent enantiomeric excess using this system.
- Kim, Geon-Hee,Jeon, Hyunwoo,Khobragade, Taresh P.,Patil, Mahesh D.,Sung, Sihyong,Yoon, Sanghan,Won, Yumi,Sarak, Sharad,Yun, Hyungdon
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p. 1437 - 1440
(2019/02/06)
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- Synthesis, molecular docking and biological evaluation of novel phthaloyl derivatives of 3-amino-3-aryl propionic acids as inhibitors of Trypanosoma cruzi trans-sialidase
-
In the last two decades, trans-sialidase of Trypanosoma cruzi (TcTS) has been an important pharmacological target for developing new anti-Chagas agents. In a continuous effort to discover new potential TcTS inhibitors, 3-amino-3-arylpropionic acid derivatives (series A) and novel phthaloyl derivatives (series B, C and D) were synthesized and molecular docking, TcTS enzyme inhibition and determination of trypanocidal activity were carried out. From four series obtained, compound D-11 had the highest binding affinity value (?11.1 kcal/mol) compared to reference DANA (?7.8 kcal/mol), a natural ligand for TS enzyme. Furthermore, the 3D and 2D interactions analysis of compound D-11 showed a hydrogen bond, π-π stacking, π-anion, hydrophobic and Van der Waals forces with all important amino acid residues (Arg35, Arg245, Arg314, Tyr119, Trp312, Tyr342, Glu230 and Asp59) on the active site of TcTS. Additionally, D-11 showed the highest TcTS enzyme inhibition (86.9% ± 5) by high-performance ion exchange chromatography (HPAEC). Finally, D-11 showed better trypanocidal activity than the reference drugs nifurtimox and benznidazole with an equal % lysis (63 ± 4 and 65 ± 2 at 10 μg/mL) and LC50 value (52.70 ± 2.70 μM and 46.19 ± 2.36 μM) on NINOA and INC-5 strains, respectively. Therefore, D-11 is a small-molecule with potent TcTS inhibition and a strong trypanocidal effect that could help in the development of new anti-Chagas agents.
- Kashif, Muhammad,Chacón-Vargas, Karla Fabiola,López-Cedillo, Julio Cesar,Nogueda-Torres, Benjamín,Paz-González, Alma D.,Ramírez-Moreno, Esther,Agusti, Rosalia,Uhrig, Maria Laura,Reyes-Arellano, Alicia,Peralta-Cruz, Javier,Ashfaq, Muhammad,Rivera, Gildardo
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p. 252 - 268
(2018/07/14)
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- Characterization of a new nitrilase from Hoeflea phototrophica DFL-43 for a two-step one-pot synthesis of (S)-β-amino acids
-
A nitrilase from Hoeflea phototrophica DFL-43 (HpN) demonstrating excellent catalytic activity towards benzoylacetonitrile was identified from a nitrilase tool-box, which was developed previously in our laboratory for (R)-o-chloromandelic acid synthesis from o-chloromandelonitrile. The HpN was overexpressed in Escherichia coli BL21 (DE3), purified to homogeneity by nickel column affinity chromatography, and its biochemical properties were studied. The HpN was very stable at 30–40?°C, and highly active over a wide range of pH values (pH 6.0–10.0). In addition, the HpN could tolerate against several hydrophilic organic solvents. Steady-state kinetics indicated that HpN was highly active towards benzoylacetonitrile, giving a KM of 4.2?mM and a kcat of 170?s?1, the latter of which is ca. fivefold higher than the highest record reported so far. A cascade reaction for the synthesis of optically pure (S)-β-phenylalanine from benzoylacetonitrile was developed by coupling HpN with an ω-transaminase from Polaromonas sp. JS666 in toluene-water biphasic reaction system using β-alanine as an amino donor. Various (S)-β-amino acids could be produced from benzoylacetonitrile derivatives with moderate to high conversions (73–99%) and excellent enantioselectivity (> 99% ee). These results are significantly advantageous over previous studies, indicating a great potential of this cascade reaction for the practical synthesis of (S)-β-phenylalanine in the future.
- Zhang, Zhi-Jun,Cai, Rui-Feng,Xu, Jian-He
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p. 6047 - 6056
(2018/05/15)
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- Kinetic Resolution of Aromatic β-Amino Acids Using a Combination of Phenylalanine Ammonia Lyase and Aminomutase Biocatalysts
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An enzymatic strategy for the preparation of (R)-β-arylalanines employing phenylalanine aminomutase and ammonia lyase (PAM and PAL) enzymes has been demonstrated. Candidate PAMs with the desired (S)-selectivity from Streptomyces maritimus (EncP) and Bacillus sp. (PabH) were identified via sequence analysis using a well-studied template sequence. The newly discovered PabH could be linked to the first ever proposed biosynthesis of pyloricidin-like secondary metabolites and was shown to display better β-lyase activity in many cases. In spite of this, a method combining the higher conversion of EncP with a strict α-lyase from Anabaena variabilis (AvPAL) was found to be more amenable, allowing kinetic resolution of five racemic substrates and a preparative-scale reaction with >98% (R) enantiomeric excess. This work represents an improved and enantiocomplementary method to existing biocatalytic strategies, allowing simple product separation and modular telescopic combination with a preceding chemical step using an achiral aldehyde as starting material. (Figure presented.).
- Weise, Nicholas J.,Ahmed, Syed T.,Parmeggiani, Fabio,Turner, Nicholas J.
-
supporting information
p. 1570 - 1576
(2017/05/05)
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- Influence of the aromatic moiety in α- And β-arylalanines on their biotransformation with phenylalanine 2,3-aminomutase from: Pantoea agglomerans
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In this study enantiomer selective isomerization of various racemic α- and β-arylalanines catalysed by phenylalanine 2,3-aminomutase from Pantoea agglomerans (PaPAM) was investigated. Both α- and β-arylalanines were accepted as substrates when the aryl moiety was relatively small, like phenyl, 2-, 3-, 4-fluorophenyl or thiophen-2-yl. While 2-substituted α-phenylalanines bearing bulky electron withdrawing substituents did not react, the corresponding substituted β-aryl analogues were converted rapidly. Conversion of 3- and 4-substituted α-arylalanines happened smoothly, while conversion of the corresponding β-arylalanines was poor or non-existent. In the range of pH 7-9 there was no significant influence on the conversion of racemic α- or β-(thiophen-2-yl)alanines, whereas increasing the concentration of ammonia (ammonium carbonate from 50 to 1000 mM) inhibited the isomerization progressively and decreased the amount of the by-product (i.e. (E)-3-(thiophen-2-yl)acrylic acid was detected). In all cases, the high ee values of the products indicated excellent enantiomer selectivity and stereospecificity of the isomerization except for (S)-2-nitro-α-phenylalanine (ee 92%) from the β-isomer. Substituent effects were rationalized by computational modelling revealing that one of the main factors controlling biocatalytic activity was the energy difference between the covalent regioisomeric enzyme-substrate complexes.
- Varga, Andrea,Bánóczi, Gergely,Nagy, Botond,Bencze, László Csaba,To?a, Monica Ioana,Gellért, ákos,Irimie, Florin Dan,Rétey, János,Poppe, László,Paizs, Csaba
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p. 56412 - 56420
(2016/07/06)
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- Synthesis and biological evaluation of 3-phenyl-3-aryl carboxamido propanoic acid derivatives as small molecule inhibitors of retinoic acid 4-hydroxylase (CYP26A1)
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All-trans-retinoic acid (ATRA), the biologically active metabolite of vitamin A, is used medicinally for the treatment of hyperproliferative diseases and cancers. However, it is easily metabolized. In this study, the leading compound S8 was found based on virtual screening. To improve the activity of the leading compound S8, a series of novel S8 derivatives were designed, synthesized and evaluated for their in vitro biological activities. All of the prepared compounds showed that substituting the 5-chloro-3-methyl-1-phenyl-1H-pyrazole group for the 2-tertbutyl-5-methylfuran scaffold led to a clear increase in the biological activity. The most promising compound 32, with a CYP26A1 IC50 value of 1.36 μM (compared to liarozole (IC50 = 2.45 μM) and S8 (IC50 = 3.21 μM)) displayed strong inhibitory and differentiation activity against HL60 cells. In addition, the study focused on the effect of β-phenylalanine, which forms the coordination bond with the heme of CYP26A1. These studies suggest that the compound 32 can be used as an appropriate candidate for future development.
- Zhao, Dongmei,Sun, Bin,Ren, Jinhong,Li, Fengrong,Song, Shuai,Lv, Xuejiao,Hao, Chenzhou,Cheng, Maosheng
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p. 1356 - 1365
(2015/03/04)
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- The bacterial ammonia lyase EncP: A tunable biocatalyst for the synthesis of unnatural amino acids
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Enzymes of the class I lyase-like family catalyze the asymmetric addition of ammonia to arylacrylates, yielding high value amino acids as products. Recent examples include the use of phenylalanine ammonia lyases (PALs), either alone or as a gateway to deracemization cascades (giving (S)- or (R)-α-phenylalanine derivatives, respectively), and also eukaryotic phenylalanine aminomutases (PAMs) for the synthesis of the (R)-β-products. Herein, we present the investigation of another family member, EncP from Streptomyces maritimus, thereby expanding the biocatalytic toolbox and enabling the production of the missing (S)-β-isomer. EncP was found to convert a range of arylacrylates to a mixture of (S)-α- and (S)-β-arylalanines, with regioselectivity correlating to the strength of electron-withdrawing/-donating groups on the ring of each substrate. The low regioselectivity of the wild-type enzyme was addressed via structure-based rational design to generate three variants with altered preference for either α- or β-products. By examining various biocatalyst/substrate combinations, it was demonstrated that the amination pattern of the reaction could be tuned to achieve selectivities between 99:1 and 1:99 for β:α-product ratios as desired.
- Weise, Nicholas J.,Parmeggiani, Fabio,Ahmed, Syed T.,Turner, Nicholas J.
-
supporting information
p. 12977 - 12983
(2015/10/28)
-
- Enantioselective acylation of β-phenylalanine acid and its derivatives catalyzed by penicillin G acylase from alcaligenes faecalis
-
This study developed a simple, efficient method for producing racemic β-phenylalanine acid (BPA) and its derivatives via the enantioselective acylation catalyzed by the penicillin G acylase from Alcaligenes faecalis (Af-PGA). When the reaction was run at 25°C and pH 10 in an aqueous medium containing phenylacetamide and BPA in a molar ratio of 2:1, 8 U/mL enzyme and 0.1 M BPA, the maximum BPA conversion efficiency at 40 min only reached 36.1%, which, however, increased to 42.9% as the pH value and the molar ratio of phenylacetamide to BPA were elevated to 11 and 3:1, respectively. Under the relatively optimum reaction conditions, the maximum conversion efficiencies of BPA derivatives all reached about 50% in a relatively short reaction time (45-90 min). The enantiomeric excess value of product (eep) and enantiomeric excess value of substrate (ees) were all above 98% and 95%, respectively. These results suggest that the method established in this study is practical, effective, and environmentally benign and may be applied to industrial production of enantiomerically pure BPA and its derivatives.
- Li, Dengchao,Ji, Lilian,Wang, Xinfeng,Wei, Dongzhi
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p. 207 - 216
(2013/04/23)
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- Carica papaya lipase catalysed resolution of β-amino esters for the highly enantioselective synthesis of (S)-dapoxetine
-
An efficient synthesis of the (S)-3-amino-3-phenylpropanoic acid enantiomer has been achieved by Carica papaya lipase (CPL) catalysed enantioselective alcoholysis of the corresponding racemic N-protected 2,2,2-trifluoroethyl esters in an organic solvent. A high enantioselectivity (E > 200) was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. Based on the resolution of a series of amino acids, it was found that the structure of the substrate has a profound effect on the CPL-catalysed resolution. The enantioselectivity and reaction rate were significantly enhanced by switching the conventional methyl ester to an activated trifluoroethyl ester. When considering steric effects, the substituted phenyl and amino groups should not both be large for the CPL-catalysed resolution. The mechanism of the CPL-catalysed enantioselective alcoholoysis of the amino acids is discussed to delineate the substrate requirements for CPL-catalysed resolution. Finally, the reaction was scaled up, and the products were separated and obtained in good yields (≥ 80 %). The (S)-3-amino-3- phenylpropanoic acid obtained was used as a key chiral intermediate in the synthesis of (S)-dapoxetine with very high enantiomeric excess (> 99 %). A carica papaya lipase catalysed resolution of N-protected β-phenylalanine esters has been developed. High enantioselectivity was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. After 50 % conversion, the products were separated and used as key chiral intermediates for the synthesis of (S)-dapoxetine with > 99 % ee. Copyright
- You, Pengyong,Qiu, Jian,Su, Erzheng,Wei, Dongzhi
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p. 557 - 565
(2013/03/13)
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- Annulation of 2H-pyran onto 1-Oxa- or 1-azacyclohexane-2,4-diones and their analogues via sequential condensation with -substituted enals and 6π-electrocyclization
-
2H-Pyrans are constructed on a 1-oxa- or 1-azacyclohexane-2,4-dione core via Knoevenagel condensation with enals followed by 6π.electrocyclization, which are readily catalyzed with ethylenediammonium diacetate. This formal [3 + 3] strategy constitutes CO
- Hossain, Md. Imran,Shaban, Elkhabiry,Ikemi, Taku,Peng, Wei,Kawafuchi, Hiroyuki,Inokuchi, Tsutomu
-
supporting information
p. 870 - 879
(2013/08/15)
-
- Mechanism-inspired engineering of phenylalanine aminomutase for enhanced β-regioselective asymmetric amination of cinnamates
-
Turn to switch: A mutant of phenylalanine aminomutase was engineered that can catalyze the regioselective amination of cinnamate derivatives (see scheme, red) to, for example, β-amino acids. This regioselectivity, along with the X-ray crystal structures, suggests two distinct carboxylate binding modes differentiated by Cβi￡Cipso bond rotation, which determines if β- (see scheme) or α-addition takes place. Copyright
- Wu, Bian,Szymanski, Wiktor,Wybenga, Gjalt G.,Heberling, Matthew M.,Bartsch, Sebastian,Dewildeman, Stefaan,Poelarends, Gerrit J.,Feringa, Ben L.,Dijkstra, Bauke W.,Janssen, Dick B.
-
supporting information; experimental part
p. 482 - 486
(2012/03/22)
-
- Development of a commercial process for (S)-β-phenylalanine (1)
-
The development of a commercial manufacturing route for (S)-β-phenylalanine 8, a key pharmaceutical building block, is described. The different approaches which were investigated, based on catalytic asymmetric hydrogenation of enamide intermediates and on biocatalysis using acylase and lipase hydrolyses, are compared. The lipase resolution route was chosen for scale-up, and the final two-step process, based on readily available raw materials, is shown to be robust at full manufacturing scale
- Grayson, J. Ian,Roos, Juergen,Osswald, Steffen
-
scheme or table
p. 1201 - 1206
(2011/12/16)
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- Stereoselective chemoenzymatic preparation of β-amino esters: Molecular modelling considerations in lipase-mediated processes and application to the synthesis of (S)-dapoxetine
-
A wide range of optically active 3-amino-3-arylpropanoic acid derivatives have been prepared by means of a stereoselective chemoenzymatic route. The key step is the kinetic resolution of the corresponding β-amino esters. Although the enzymatic acylations of the amino group with ethyl methoxyacetate showed synthetically useful enantioselectivities, the hydrolyses of the ester group catalyzed by lipase from Pseudomonas cepacia have been identified as the optimal processes concerning both activity and enantioselectivity. The enantiopreference of this lipase in these reactions has been explained, at the molecular level, by using a fragment-based approach in which the most favoured binding site for a phenyl ring and the most stable conformation of the 3-aminopropanoate core nicely match the (S)-configuration of the major products. The conversion and enantioselectivity values of the enzymatic reactions have been compared in order to understand the influence of the different substitution patterns present in the phenyl ring. This chemoenzymatic route has been successfully applied to the preparation of a valuable intermediate in the synthesis of (S)-dapoxetine, which has been chemically synthesised in excellent optical purity.
- Rodriguez-Mata, Maria,Garcia-Urdiales, Eduardo,Gotor-Fernandez, Vicente,Gotor, Vicente
-
supporting information; experimental part
p. 395 - 406
(2010/06/15)
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- Efficient tandem biocatalytic process for the kinetic resolution of aromatic β-amino acids
-
We describe a simple and efficient enzymatic tandem reaction for the preparation of enantiomerically pure β-phenylalanine and its analogues from the corresponding racemates. In this process, phenylalanine aminomutase (PAM) catalyzes the stereoselective isomerization of (R)-β-phenylalanines to (S)-a-phenylalanines, which are in situ transformed to cinnamic acids by phenylalanine ammonia lyase (PAL). Preparative scale conversions are done with a mutated PAM with enhanced catalytic activity.
- Wu, Bian,Szymanski, Wiktor,De Wildeman, Stefaan,Poelarends, Gerrit J.,Feringa, Ben L.,Janssen, Dick B.
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supporting information; experimental part
p. 1409 - 1412
(2010/08/19)
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- Phenylalanine aminomutase-catalyzed addition of ammonia to substituted cinnamic acids: A route to enantiopure α- and β-amino acids
-
(Chemical Equation Presented) An approach is described for the synthesis of aromatic α- and β-amino acids that uses phenylalanine aminomutase to catalyze a highly enantioselective addition of ammonia to substituted cinnamic acids. The reaction has a broad scope and yields substituted α- and β-phenylalanines with excellent enantiomeric excess. The regioselectivity of the conversion is determined by substituents present at the aromatic ring. A box model for the enzyme active site is proposed, derived from the influence of the hydrophobicity of substituents on the enzyme affinity toward various substrates.
- Szymanski, Wiktor,Wu, Bian,Weiner, Barbara,De Wildeman, Stefaan,Feringa, Ben L.,Janssen, Dick B.
-
supporting information; experimental part
p. 9152 - 9157
(2010/03/01)
-
- 3-AMINO-3-ARYLPROPIONIC ACID n-ALKYL ESTERS, PROCESS FOR PRODUCTION THEREOF, AND PROCESS FOR PRODUCTION OF OPTICALLY ACTIVE 3-AMINO-3-ARYLPROPIONIC ACIDS AND ESTERS OF THE ANTIPODES THERETO
-
The present invention is to provide an n-alkyl 3-amino-3-arylpropionate represented by the formula (I): wherein Ar1 represents an aryl group which may have a substituent(s), provided that a phenyl group and 4-methoxyphenyl group are excluded, R1 represents an n-propyl group or an n-butyl group, and a process for preparing the same, and its optically active compound and an optically active (S or R)-3-amino-3-arylpropionic acid represented by the formula (III-a): wherein Ar represents an aryl group which may have a substituent(s), and * represents an asymmetric carbon, and a process for preparing an optically active n-alkyl (R or S)-3-amino-3-arylpropionate represented by the formula (IV-a): wherein Ar and R1 have the same meanings as defined above, * represents an asymmetric carbon, provided that it has a reverse absolute configuration to the compound of the formula (III-a).
- -
-
Page/Page column 31
(2008/06/13)
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- A new route to enantiopure β-aryl-substituted β-amino acids and 4-aryl-substituted β-lactams through lipase-catalyzed enantioselective ring cleavage of β-lactams
-
A simple and efficient direct enzymatic method was developed for the synthesis of 4-aryl-substituted β-lactams and the corresponding β-amino acid enantiomers through the CAL-B (lipase B from Candida antarctica)-catalyzed enantioselective (E > 200) ring cleavage of the corresponding racemic β-lactams with 1 equiv. of H2O in i-Pr2O at 60°C. The product (R)-β-amino acids (ee ≥ 98%, yields ≥ 42%) and unreacted (S)-β-lactams (ee ≥ 95%, yields ≥ 41%) could be easily separated. The ring opening of enantiomeric β-lactams with 18% HCl afforded the corresponding enantiopure β-amino acid hydrochlorides (ee ≥ 99%).
- Forro, Eniko,Paal, Tihamer,Tasnadi, Gabor,Fueloep, Ferenc
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p. 917 - 923
(2007/10/03)
-
- Synthesis and anticonvulsant activity of some new hexahydropyrimidine-2,4- dione derivatives
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In this study, twelve new hexahydropyrimidine-2,4-dione derivatives were synthesized and screened for their anticonvulsant activities. All the compounds (7a-l) which have 6-arylhexahydropyrimidine-2,4-dione and N,N-disubstituted dithiocarbamate structures were prepared by the reaction with appropriate 3-(2-chloroethyl)-6-arylhexahydropyrimidine-2,4-diones and the corresponding N,N-disubstituted dithiocarbamate potassium salts. The structure of the synthesized compounds was confirmed by UV, IR, 1H-NMR and elemental analysis. Their anticonvulsant activities were determined by maximal electroshock (MES), subcutaneous pentetrazol (metrazol, scMet) and rotorod toxicity tests for neurological deficits. According to the activity studies, 6-(4-chlorophenyl)hexahydropyrimidine-2,4-dione derivatives (7e-h) were found to be highly protective against MES and scMet. Neurotoxicity was not observed in any of the tested compounds.
- Septioglu, Ebubekir,Aytemir, Mutlu Dilsiz,Calis, Uensal
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p. 259 - 264
(2007/10/03)
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- Kinetic resolution of oxazinones: An organocatalytic approach to enantiomerically pure β-amino acids
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(Chemical Equation Presented) A profitable split: An organocatalytic resolution converts readily available racemic oxazinones 1 into valuable enantiomerically pure β-amino acid derivatives 2 (> 99% ee of the remaining 1 at 53% conversion; 88% ee of the ester 2). This catalytic ring-opening reaction requires as little as 1 mol% of the modular and readily accessible thiourea organocatalyst 3.
- Berkessel, Albrecht,Cleemann, Felix,Mukherjee, Santanu
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p. 7466 - 7469
(2007/10/03)
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- Solid-phase synthesis of a nonpeptide RGD mimetic library: New selective αvβ3 integrin antagonists
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The solid-phase synthesis of a low molecular weight RGD mimetic library is described. Activities of the compounds in inhibiting the interaction of ligands, vitronectin and fibrinogen, with isolated immobilized integrins αvβ3 and αIIbβ3 were determined in a screening assay. Highly active and selective nonpeptide αvβ3 integrin antagonists with regard to orally bioavailability were developed, based on the aza-glycine containing lead compound 1. An important variation is the substitution of the aspartic amide of 1 by an aromatic residue. Furthermore, different guanidine mimetics have been incorporated to improve the pharmacokinetic profile. Exchange of the β-amino acid NH by a methylene moiety in one set of RGD mimetics leads to the azacarba analogue compounds representing a novel peptidomimetic approach, which should increase the metabolic stability.
- Sulyok,Gibson,Goodman,H?lzemann,Wiesner,Kessler
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p. 1938 - 1950
(2007/10/03)
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- Potential GABAB receptor antagonists. IX: The synthesis of 3-amino-3-(4-chlorophenyl)propanoic acid, 2-amino-2-(4-chlorophenyl)ethylphosphonic acid and 2-amino-2-(4-chlorophenyl)ethanesulfonic acid
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This paper describes the synthesis of 3-amino-3-(4-chlorophenyl)propanoic acid and the corresponding phosphonic and sulfonic acids, lower homologues of baclofen, phaclofen and saclofen respectively. The chlorinated acids were all weak specific antagonists of GABA at the GABAB receptor, with the sulfonic acid (pA2 4·0) being stronger than the phosphonic acid (pA2 3·8) and carboxylic acid (pA2 3·5).
- Abbenante, Giovanni,Hughes, Robert,Prager, Rolf H.
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p. 523 - 527
(2007/10/03)
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- Biocatalytic approach to enatiomerically pure β-amino acids
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β-Aryl-β-amino acids were prepared in good chemical yield and high enantiomeric purity (> 95% ee) via penicillin acylase-catalyzed hydrolysis of the corresponding N-phenylacetyl derivatives. The (R)-enantiomers were the fast-reacting isomers in all cases studied. The biocatalytic procedure described employs a very simple set of reactions using inexpensive commercially available chemicals and enzyme, and could be easily scaled up.
- Soloshonok,Fokina,Rybakova,Shishkina,Galushko,Sorochinsky,Kukhar,Savchenko,Svedas
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p. 1601 - 1610
(2007/10/02)
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- SYNTHESIS OF 6-ARYL-4-HYDROXYPIPERIDIN-2-ONES AND A POSSIBLE APPLICATION TO THE SYNTHESIS OF A NOVEL HMG-CoA REDUCTASE INHIBITOR
-
A series of 6-aryl-4-hydroxypiperidin-2-ones (11a-11g) were synthesised with the key step being a Dieckmann cyclisation of the appropriate methyl 3-(ethoxycarbonylacetylamino)-3-(substituted) propionate (8a-8g) and this new synthetic route was successfully applied to the synthesis of 4-hydroxy-6-(2-phenylethyl)piperidin-2-one (11h).The application of this strategy to the synthesis of the putative HMG-CoA reductase inhibitor 6--4-hydroxypiperidin-2-one (11i) was attempted, but failed during the Dieckmann cyclisation of methyl 3-(ethoxycarbonylacetylamino)- 3-propionate (8i).An alternative synthesis of a 1:1 diastereomeric mixture of (11i) was achieved by the reductive cleavage of the isoxazoline (24) with Raney nickel.The mixture of diastereoisomers (11i) was inactive in-vitro and in-vivo (rat) against HMG-CoA reductase
- Ashton, Michael J.,Hills, Susan J.,Newton, Christopher G.,Taylor, John B.,Tondu, Sylvie C. D.
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p. 1015 - 1035
(2007/10/02)
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