• 대한약리학회지
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• 제32권2호
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• pp.169-175
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• 1996

The reactivity of the sulfhydryl (thiol) group of homocysteine has been associated with an Increased risk of atherosclerosis, thrombosis and stroke. Thiols also react with nitric oxide (NO, an endothelium-derived relaxing factor (EDRF) ), forming S-nitrosothiols that have been reported to have potent vasodilatory and antiplatelet effects and been expected to decrease adverse vascular effects of homocysteine. The present study was aimed to Investigate whether the S-nitrosation of homocysteine modulates the neurotoxic effects of homocysteine. An 18 hour-exposure of cultured rat cortical neurons to homocysteine ( >1 mM) resulted in a significant neuronal cell death. At comparable concentrations ( <10 mM), however, S-nitrosohomocysteine did not induce neuronal cell death. Furthermore, S-nitrosohomocysteirle partially blocked NMDA-mediated neurotoxicity. S-nitrosohomocysteine also decreased NMDA-mediated increases in intracellular calcium concentration. The present data indicate that in brain nitric oxide produced from neuronal and nonneuronal cells can modulate the potential, adverse properties of homocysteine.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2381-2386
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• 2009

The tetrakis(thio)-substituted-1,4-benzoquinone products 4a-e, 6, 7, and the mono(alkoxy)-tris(thio)-substituted-1,4- benzoquinone products 5a-e and 8a-e were synthesized from the reactions of p-chloranil with some thiols and mixture of two different thiol compounds in alcohol in the presence of $Na_2CO_3$ at room temperature. The structures of the novel S,S,S,S- and S,S,S,O- substituted products, which were obtained by the reactions of p-chloranil as a starting compound with n-propanethiol, n-pentanethiol, n-decanethiol, n-dodecanethiol, 2-methyl-2-propanethiol, and mixture of n-decanethiol and n-cyclohexanethiol as S-nucleophiles, were characterized by spectroscopic methods.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.873-877
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• 2004

The relationship between the behaviors of c.c.lipase back-extraction and their percolation phenomena by using AOT reverse micellar systems (RVMS) has been studied by the addition of a small amount of additives to organic phase such as thiols and nonionic-surfactants focusing on micelle-micelle interactions. The values of ${\beta}_t$ defined by the variation of percolation processes and back-extraction behaviors of c.c.lipase have a good linear correlation. The hydrophobicity of additive molecules suppressing the cluster formation of reverse micelles (high values of ${\beta}_t$) improved the back-extraction behavior of c.c.lipase. The back-extraction fraction and its rate of c.c.clipase are increased with decreasing of the value of hydrophilic lipophilic balance (HLB) and increasing of the hydrophobicity per additive molecules added to reverse micellar systems (RVSM) in the same additives concentration.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3692-3695
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• 2011

Poly(N,N'-Dichloro-N-ethyl-benzene-1,3-disulfonamide) (PCBS) and N,N,N',N'-Tetrachlorobenzene-1,3-disulfonamide (TCBDA) were found to be a mild and efficient reagent for the direct oxidative conversion of sulfur compounds to the corresponding arenesulfonyl chlorides in good to excellent yields through the oxidative chlorination. The overall process is simple, practical, and it provides convenient access to a variety of aryl or heteroarylsulfonyl chlorides. The mild reaction conditions and the broad substrate scope render this method attractive, and complementary to existing syntheses of aryl or heteroarylsulfonyl chlorides.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.115-117
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• 1988

The addition of L-cysteine without blocking amino and carboxyl groups to${\beta},{\beta}$-dinitrostyrene derivatives(11a-e) were investigated. ${\beta},{\beta}$ -Dinitrostyrene derivatives(11a-e) easily undergo addition reactions with L-cysteine to from s-(2,2-dinitro-1-phenylethyl)-L-cysteine(12a), s-[2,2-dinitro-1-(p-methyl)phenylethyl]-L-cysteine (12b), s-[2,2-dinitro-1-(p-methoxy)phenylethyl]-L-cystein e(12c), s-[2,2-dinitro-1-(p-chloro)phenylethyl]-L-cysteine (12d) and s-[2,2-dinitro-1-(p-nitro)phenylethyl]-L-cysteine( 12a), respectively. The structure of adducts were confirmed by means of spectral data, molecular weight measurement and elemental analysis.

• Bulletin of the Korean Chemical Society
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• 제5권1호
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• pp.21-23
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• 1984

The addition reactions of thioglycolic acid to ${\omega}$, ${\omega}$-diacetylstyrene derivatives were investigated. ${\omega}$, ${\omega}$-Diacetylstyrene derivatives easily undergo addition reactions with thioglycolic acid to form s-(2, 2-diacetyl-1-phenylethyl)-thiogycolic acid, s-[2,2-diacetyl-1-(methyl) phenylethyl]-thioglycolic acid, s-[2,2-diacetyl-1-(p-methoxy) phenylethyl]-thioglycolic acid and s-[2,2-diacetyl-1-(p-chloro) phenylethyl]-thioglycolic acid, respectively. The structures of these compounds were identified by neutralization equivalent, UV, IR, and NMR spectral data.

• Bulletin of the Korean Chemical Society
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• 제3권2호
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• pp.70-76
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• 1982

Synthetic utility of 1-fluoro-2,4,6-trinitrobenzene (FTNB) as a condensing agent was investigated. The use of FTNB and DMAP was found to be very effective for direct esterification of carboxylic acids with alcohols or thiols. However, this system was not very effective for macrolactonization. Reaction of 2,4,6-trinitrophenyl esters with several nucleophiles was investigated briefly. Plausible reaction mechanisms of esterification are presented. It seems that the reaction proceeds via the intermediacy of 2,4,6-trinitrophenyl esters by initial formation of 2',4',6'-trinitrophenyl-4-dimethylaminopyridinium salt from which the trinitrophenyl group is transferred to the carboxylic acid.

• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.743-749
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• 1993

The approximate rates and stoichiometry of the reaction of excess lithium tris(dihexylamino)aluminum hydride(LTDHA) with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0$^{\circ}$C) were studied in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTDHA was also compared with those of the parent lithium aluminum hydride(LAH), lithium tris(diethylamino)aluminum hydride(LTDEA), and lithium tris(dibutylamino)aluminum hydride(LTDBA). In general, the reactivity toward organic functionalities is in order of $LAH{\gg}LTDEA{\geq}LTDBA>LTDHA$. LTDHA shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, epoxides, and tertiary amides readily. Anthraquinone is cleanly reduced to 9,10-dihydro-9,10-anthracenediol without hydrogen evolution, whereas p-benzoquinone in inert to LTDHA. In addition to that, disulfides are also readily reduced to thiols without hydrogen evolution. However, carboxylic acids, anhydrides, nitriles, and primary amides are reduced slowly. Especially, this reagent reduces aromatic nitriles to the corresponding aldehydes in good yields.

• Bulletin of the Korean Chemical Society
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• 제22권6호
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• pp.553-558
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• 2001

A stereoselective synthesis of $1\beta-aminocarbapenems$ (11a-c) starting from-4-acetoxy-2-axetidinone derivative 4 is described. 4-Acetoxy-2-azetidinone derivative (4) was reacted with lithium enolate of benzophenone limine of glycine phenyl ester (5f) to give alkylated product (R)-6f in good yield with high diastereoselectivity. The alkylated procudt (R)-6f was transformed to thioesters (7a-c) by transesterification with thiols, Thioesters (7a-c) were converted to their oxalimides (8a-c), followed by the phosphite-mediated reductive cyclization to give carbapenems (9a-c). Removal of all protecting groups of carbapenems (9a-c) afforded $1\beta-aminocarbapenems$ (11a-c).

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.644-649
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• 1991

The approximate rates and stoichiometry of the reaction of excess lithium tris(dibutylamino)aluminum hydride (LT-DBA) with selected organic compounds containing representative functional groups under standardized conditions (tetrahydrofuran, $0^{\circ}C$) were studied in order to characterize the reducing characteristics of the reagent for selective reductions. The reducing ability of LTDBA was also compared with those of the parent lithium aluminum hydride and the alkoxy derivatives. The reagent appears to be much milder than the parent reagent, but stronger than lithium tri-t-butoxyaluminohydride in reducing strength. LTDBA shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, acid chlorides, epoxides, and amides readily. In addition to that, ${\alpha},{\beta}$-unsaturated aldehyde is reduced to ${\alpha},{\beta}$-unsaturated alcohol. Quinones are reduced to the corresponding diols without evolution of hydrogen. Tertiary amides and aromatic nitriles are converted to aldehydes with a limiting amount of LTDBA. Finally, disulfides and sulfoxides are readily reduced to thiols and sulfides, respectively, without hydrogen evolution.