• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.588-592
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• 1988

A chiral recognition was observed in aminolysis of 3-acyl-4(S)-isopropyl-1,3-thiazolidine-2-thione by racemic amine to give an optically active amide (S-excess) and amine (R-excess). This procedure can be applied to synthesis of macrocyclic diamide macrocyclic spermidine alkaloid, and peptide. The rate of this aminolysis is remarkably affected by steric surrounding; completion of reaction can be easily judged by the disappearance of the original yellow color of 4(S)-AITT. These features of the aminolysis suggested a potential recognition racemic amines by a chiral 4 (S)-AITT derivative. Thus 4 (S)-AITT was synthesized from 4 (S)-isopropyl-1, 3-thiazolidine-2-thione and carboxylic acids.

• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.936-942
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• 2014

Using racemic (R,S)-2-(4-chlorophenyl)-3-methylbutyramide, an intermediate for the chiral pyrethroid insecticide Esfenvalerate, as a sole nitrogen source in a minimal medium, several strains with high enatioselectivity (${\geq}98%$) were isolated by enrichment techniques. One of the strains, LG 31-3, was identified as Burkholderia multivorans, based on physiological and morphological tests by a standardized Biolog station for carbon source utilization. A novel amidase was purified from B. mutivorans LG 31-3 and characterized. The enzyme exhibited (S)-selective amidase activity on racemic (R,S)-2-(4-chlorophenyl)-3-methylbutyramide. Addition of the racemic amide induced the production of the enantioselective amidase. The molecular mass of the amidase on SDS-PAGE analysis was shown to be 50 kDa. The purified amidase was subjected to proteolytic digestion with a modified trypsin. The N-terminal and internal amino acid sequences of the purified amidase showed a high sequence homology with those deduced from a gene named YP_366732.1 encoding indole acetimide hydrolase from Burkholderia sp. 383.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.149-152
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• 1988

A mixture of (Z,Z)-3,13-octadecadien-1-yl acetate(1) and its (E,Z)-isomer(2), the sex pheromone of the cherry tree borer, Synanthedon hector Butler was synthesized. (Z)-11-Octadecen-1-al(3) was prepared from 1,10-decandiol. The Wittig reaction the above aldehyde3 with carboethoxymethylenetriphenylphosphorane, or the Wadsworth-Emmons reaction of the above aldehyde3 with the anion of triethylphosphonoacetate gave ethyl (Z,Z)-2,13-octadecadienoate and its (E,Z)-isomer. Deconjugative protonation of ethyl (Z,Z)-2,13-octadecadienoate and its (E,Z)-isomer with potassium hexamethyldisilazide followed by aqueous ammonium chloride work-up afforded stereoselectiv디y ethyl (E,Z)-3,13-octadecadienoate and its (Z,Z)-isomer, respectively, of which stereoselectivity was adjusted to give the product in the required ratio. Exposure of the above deconjugated ester to excess lithium aluminium hydride resulted in formation of the penultimate (Z,Z)-3,13-octadecadien-1-ol and its (E,Z)-isomer. Acetylation of the desired alcohols afford the final products, (Z,Z)-3,13-octadecadien-1-yl acetate(1) and its (E,Z)-isomer(2).

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.218-226
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• 2007

The stereoselective synthesis of chiral terminal epoxides is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new dinuclear chiral Co (salen) complexes bearing gallium-, indium- and tallium-chloride have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of dinuclear complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides having ether or ester groups by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99% ee). The dimeric structured chiral salen showed remarkably enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues. The system described in this work is very efficient for the synthesis of chiral epoxide and 1,2-diol intermediates

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.562-567
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• 2007

The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their use as versatile starting materials as well as chiral intermediates. In this study, new polymeric chiral Co(salen) complexes bearing tallium (III)chloride and iron (III)chloride (ferric chloride) have been synthesized and characterized. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides using water and phenol derivatives as nucleophiles. The easily prepared polymeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ and phenol nucleophiles, providing enantiomerically enriched terminal epoxides (> 98% ee). The system described in this work is very efficient for the synthesis of chiral epoxide, 1,2-diol and ${\alpha}$-aryloxy alcohol intermediates.

• Journal of the Korean Chemical Society
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• v.30 no.6
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• pp.548-552
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• 1986

A stereoselective synthesis of 3-phenoxybenzyl (${\pm}$)-cis and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-1-cyclopropanecarboxylic acid starting from readily available 2-methyl-3-buten-2-ol($\underline{2}$) is described. Allylic rearrangement of 2-methyl-3-buten-2-ol, in the presence of acetic acid and acetic anhydride gave 3-methyl-2-butenyl acetate($\underline{3}$). The [3,3] sigmatropic rearrangement of the allyl acetate($\underline{3}$), as the silylketene acetal, produced the ${\gamma},\;{\delta}$-unsaturated acid($\underline{4}$). Treatment of 3,3-dimethyl-4-pentenoic acid($\underline{4}$) with SOCl2 followed by esterification with 3-phenoxybenzyl alcohol yielded 3, 3-dimethyl-4-pentenoic acid ester($\underline{5}$). Addition of carbon tetrachloride to the olefin ester($\underline{6}$) furnished 4,6,6,6-tetrachloro-3,3-dimethylhexanoic acid ester ($\underline{7}$). Cyclization with potassium t-butoxide and elimination of hydrogen chloride afforded 3-phenoxybenzyl (${\pm}$) cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-1-cyclopropanecarboxylic acid.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.111-115
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• 2015

Two new analogs of bestatin were prepared from $\small{D}$-leucine and $\small{D}$-valine in a stereoselective and efficient way. An aminopeptidase inhibitor bestatin shows significant biological effects on immunomodulation and is marketed for the treatment of acute myelocytic leukemia. The key intermediates, trans-oxazolidine methyl esters 2a and 2b, were obtained with more than 20 to 1 stereoselectivity in a one-pot procedure by the three cascade reactions between N-hydroxymethyl protected ${\alpha}$-amino aldehydes (4a and 4b) and phenylsulfonylnitromethane ($PhSO_2CH_2NO_2$) and the following in-situ ozonolysis. Basic hydrolysis of 2a and 2b, and then the peptide coupling with $\small{L}$-Leu-OMe produced the protected derivatives of two new bestatin analogs, 3a and 3b, respectively. The new isobutyl and isopropyl analogs of bestatin (1a and 1b) were produced in overall 51% and 38% yields, respectively, with high stereoselectivity from the corresponding protected ${\alpha}$-amino aldehydes 4 in a six-step process.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.647-661
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• 2005

The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this review, we investigate the research and development trend in the asymmetric ring opening reactions using cobalt salen catalysts. Hydrolytic kinetic resolution (HKR) technology is the very prominent way to prepare optically pure terminal epoxides among available methods. We have synthesized homogeneous and heterogeneous chiral dinuclear salen complexes and demonstrated their catalytic activity and selectivity for the asymmetric ring opening of terminal epoxides with variety of nucleophiles and for asymmetric cyclization to prepare optically pure terminal epoxides in one step. The resolved ring opened product combined with ring closing in the presence of base and catalyst afforded the enantioriched terminal epoxides in quantitaive yield. Potentially, these catalysts are using on an industrial scale to produce chiral intermediates. The experimental results of HKR technology applied to the synthesis of various chiral compounds are presented in this paper.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.552-559
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• 2008

Ethyl (S)-4-chloro-3-hydroxybutyrate is an intermediate for the synthesis of Atorvastatin, a chiral drug used for hypercholesterolemia. A Rhodococcus erythropolisstrain (No.7) able to convert 4-chloro-3-hydroxybutyronitrile into 4-chloro-3-hydroxybutyric acid has recently been isolated from soil. This activity has been regarded as having been caused by the successive actions of the nitrile hydratase and amidase. In this instance, the corresponding amidase gene was cloned from the R. erythropolis strain and expressed in Escherichia coli cells. A soluble active form of amidase enzyme was obtained at $18^{\circ}C$. The Ni column-purified recombinant amidase was found to have a specific activity of 3.89 U/mg toward the substrate isobutyramide. The amidase was found to exhibit a higher degree of activity when used with mid-chain substrates than with short-chain ones. Put differently, amongst the various amides tested, isobutyramide and butyramide were found to be hydrolyzed the most rapidly. In addition to amidase activity, the enzyme was found to exhibit acyltransferase activity when hydroxyl amine was present. This dual activity has also been observed in other enzymes belonging to the same amidase group (E.C. 3.5.1.4). Moreover, the purified enzyme was proven to be able to enantioselectively hydrolyze 4-chloro-3-hydroxybutyramide into the corresponding acid. The e.e. value was measured to be 52% when the conversion yield was 57%. Although this e.e. value is low for direct commercial use, molecular evolution could eventually result in this amidase being used as a biocatalyst for the production of ethyl (S)-4-chloro-3-hydroxybutyrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4940-4950
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• 2011

cis-(3R,5R)-Atorvastatin Ca (1) used for hyperlipidemia have four stereomers. However, It is very difficult to prepare stereoselective stereomers. In this paper, the reduction of 3,5-diketo atorvastatin ester (3) was performed using $Me_4NHB(OAc)_3$ in acetic acid as a reductant and showed excellent stereoselectivity in the double reduction of 3,5-diketo atorvastatin ester (3). As a result, reduction of compound 3 by $Me_4NHB(OAc)_3$ was purely obtained with cis-(3R,5R)-atorvastatin ester (4) of 1.5% and trans-(3R,5S)-atorvastatin ester (5) of 98.5%. Also, cis-(3R,5R)-atorvastatin Ca (1) and trans-(3R,5S)-atorvastatin Ca (7) were used to determine efficacy in the treatment of liver damage and hyperlipidemia induced by a high-fat diet in rats and to study the performance of the January 2010 experient was conducted. As a result, total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c), and triglyceride (TG) levels of compound 1 and 7 groups were $93.0{\pm}0.5$, $43.5{\pm}0.8$, $40.4{\pm}1.4$, $45.6{\pm}0.9\;mg/d{\ell}$ and $110.0{\pm}0.7$, $33.3{\pm}0.6$, $65.8{\pm}1.9$, $54.8{\pm}1.2\;mg/d{\ell}$, respectively. Atherogenic index (AI) and cardiac risk factor (CRF) in compound 1 and 7 were $1.14{\pm}0.05$, $2.14{\pm}0.05$ and $2.31{\pm}0.06$, $3.31{\pm}0.06$, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were $51.9{\pm}4.6$, $16.0{\pm}2.1\;IU/{\ell}$ and $75.8{\pm}4.4$, $35.1{\pm}9.7\;IU/{\ell}$. Taken together, while compound 1 treat against high-fat diet-induced hyperlipidemia by attenuating hepatic lipid depots and reducing oxidative stress, compound 7 group had a low curative effect on hyperlipidemia induced by a high-fat diet in rats. These findings suggest that new method about synthesis of stereoselective stereomers and indicate that it may consider using in a clinical trial.