• YAKHAK HOEJI
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• v.48 no.5
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• pp.272-277
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• 2004

The 2-amino-l-phenylpropanols 4∼7 were reacted with isothiocyanates to afford the 20 thioureido MAPP derivatives 8a∼11e, which were tested their cytotoxic activity by MTT assay. The cytotoxicity of alkylthioureido compounds were increased and decreased by alkyl chain length from $C_{8}$ to $C_{14}$ and of phenylthioureido compounds showed poor activity. The compounds (8b, 8c, 9b, 9c, l0b, 10c, 11b, 11c) with $C_{10}$ and $C_{12}$ alkyl chains gave stronger activity than reference compound B13. The $IC_{50}$/ of compound 8c was 1.05$\mu$M and 3 times stronger activity than B13. The stereochemistry of synthesized compounds affected very little to cytotoxic activity.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.298-300
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• 1987

The theoretical studies on the photocycloaddition reaction of 5,7-dimethoxycoumarin and 4',5'-dihydropsoralen with thymidine were carried out as a model for photosensitizing reaction of psoralen with DNA. The results are in reasonable agreement with experimental observations. The photoadducts between dimethoxycoumarin and thymidine were predicted to be $C_{4}$-cycloadducts through the cycloaddition of 3,4-pyrone double bond of dimethoxycoumarin to 5,6 double bond of thymidine. The major photoadduct of 4',5'-dihydropsoralen with thymidine has the anti head-to-head stereochemistry.

• Bulletin of the Korean Chemical Society
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• v.3 no.4
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• pp.153-157
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• 1982

$C_4$-Photocycloaddition of 8-methoxypsoralen (8-MOP) and 5,7-dimethoxycoumarin (DMC) to maleimide was studied in order to elucidate the mechanism of the photobiological activities of these molecules. The photoreaction was carried out in chloroform solution and frozen aqueous solution state. The major product was isolated and characterized by spectroscopic methods. The photoadduct between 8-MOP and maleimide was shown to be an 1:1 $C_4$-cycloadduct through the photocycloaddition of 4',5'-furyl double bond of 8-MOP to maleimide. The stereochemistry of cyclobutane ring of this photoadduct is consistent with the anti configuration. The photoadduct between DMC and maleimide was shown to be an 1:1 $C_4$-cycloadduct through the photocycloaddition of 3,4-pyrone double bond of DMC to maleimide.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.355-358
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• 1987

The reaction of t-butylithium with chlorodiphenylvinylsilane at low temperatures in hexane gave a 52% yield of the two isomeric 1,1,3,4-tetraphenyl-2,4-dineopenty-1,3-disilacyclo butanes mixture, formed by a head-to-tail dimerization of 1,1-diphenyl-2-neopentylsilene intermediate. In the presence of the trapping agents such as trimethylmethoxysilane and anthracene, the expected trapped adducts, 1-methoxy-l,l-diphenyl-2-trimethylsilyl-4,4-dimethyl-1-silapentane and 2,2-diphenyl-3-neopentyl-(5,6 : 7,8)-dibenzo-2-silabicyclo-(2.2.2)-octane, were obtained in 74% and 46% yields, respectively. These products were separated and their stereochemistry were assigned on the basis of $^1H$- and $^{13}C$-NMR data.

• Polymer(Korea)
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• v.39 no.3
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• pp.487-492
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• 2015

The effects of chemical structure of alkyl groups of norbornene carboxylic alkyl esters(methyl, octyl, 4-chlorobenzyl) and endo/exo ratios of norbornene monomers on activity of palladium catalyst and polymerization behavior were investigated. Norbornene ester monomers were synthesized from the reaction of 5-norborene-2-carboxylic acid and various alcohols. Polymerization catalyst, di-${\mu}$-chloro-bis(-methoxybicyclo[2,2,1]-hept-2-ene)palladium(II) (DCBMP), was synthesized according to the literature procedure and silver hexafluoroantimonate ($AgSbF_6$) was used as a conjugate anion source. Gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) were the principal techniques for polymer characterization and $^1H$ NMR spectroscopy was used for chemical structures determination of monomers and polymers. For all of the norbonene alkyl esters GPC data showed that when the amounts of endo isomers exceeded those of exo isomers decreased molecular weight polymers were obtained probably due to the decreased catalyst activity. Polymerizations were conducted by varying the monomer/catalyst mole ratios (100:1, 200:1, 300:1). When 300:1 monomer/catalyst ratio was employed it was possible to synthesize high molecular weight ($M_n=27500g/mol$), film forming polymer from exo-norbornene carboxylic acid octyl ester.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.119-130
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• 1993

The stereochemistry of 1,3-thiazolidine sulfoxides 1 in which 3 chiral centres are present in a molecule was elucidated by deuterium exchange and trapping reactions. 3-Acetoxy-1,3-thiazolidines 5 was oxidized to 6 and 8, corresponding $\alpha$-cis 10, $\alpha$-trans 11, $\beta$ -cis 12, and $\beta$ -trans 13 isomers were separated from their diasteromeric mixtures. Sulfoxide 10 was isomerized to more thermodynamically stable isomer 13 under neutral conditions in refluxing benzene or toluene. The methyl hydrogens of 2-methyl group in the sulfoxide 13 and those of the sulfoxide 11 were deuterated by the deuterium incorporation reactions. The intermediate sulfenic acids 25 and 26 derived from the sulfoxides 10 and 12 via sigmatropic rearrangement were trapped by 2-mercaptobenzothiazole (2-MBT) to give disufides 27 and 28 respectively. However, the sulfoxides 11 and 13 were transformed to ring expansion product dihydro-1,4-thiazine 29 under the same reaction conditions. In the presence of acid catalyst, the sulfoxides 10, 11, and 12 were converted to dihydro-1,4-thiazine 29 through the sulfoxide 13 quantitatively. The mechanisms of isomerization of sulfoxides and the formation of 29 were also discussed.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.594-602
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• 2011

The effect of ${\alpha}$-, ${\beta}$- and ${\gamma}$-picolines on the stereochemistry of the coordination compounds of lanthanide(III) nitrates derived from 4[N-(furfural)amino]antipyrine semicarbazone (FFAAPS) has been studied. The general composition of the present coordination compounds is [Ln(FFAAPS)$(NO_3)_3$Pic] (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy or Ho and Pic=${\alpha}$-, ${\beta}$- or ${\gamma}$-picolines). All these coordination compounds have been characterized by elemental analyses, molecular weight, molar conductance, magnetic susceptibility, infrared and electronic spectra. The infrared studies suggest that the FFAAPS behaves as a neutral tridentate ligand with N, N, O donor while ${\alpha}$-, ${\beta}$- or ${\gamma}$-picoline is coordinated to the lanthanide(III) ions via heterocyclic N-atom. Nitrates are bicovalently bonded in these compounds. From the electronic spectral data, nephelauxetic effect (${\beta}$), covalence factor ($b^{1/2}$), Sinha parameter (${\delta}%$) and the covalence angular overlap parameter (${\eta}$) have been calculated. Thermal stabilities of these complexes have been studied by thermogravimetric analysis. The coordination number of lanthanide(III) ions in the present compound is found to be ten. The antibacterial studies screening of the primary ligand FFAAPS and the complexes showed that the present complexes have moderate antibacterial activities.

• Journal of the Korean Magnetic Resonance Society
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• v.12 no.1
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• pp.14-25
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• 2008

To investigate the 3-bond connectivity of human brain metabolites by scalar coupling interaction through 2D-correlation spectroscopy (COSY) techniques using high field NMR spectroscopy. All NMR experiments were performed at 298K on Unity Inova 500 or 600 (Varian Inc.) equipped with a triple resonance probe head with z-shield gradient. Human brain metabolites were prepared with 10% $D_2O$. Two dimensional 2D COSY spectra were acquired with 4096 complex data points in $t_2$ and 128 or 256 increments in $t_1$ dimension. The spectral width was 9615.4 Hz and solvent suppression was achieved using presaturation using low power irradiation of the water resonance during 2s of relaxation delay. NMR data were processed using VNMRJ (Varian Instrument) software and all the chemical shifts were referenced to the methyl resonance of N-acetyl aspartate (NAA) peak at 2.0 ppm. Total 10 metabolites such as N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), glutamine (Gln), glutamate (Glu), myo-inositol (Ins), lactate (Lac), taurine (Tau), ${\gamma}$-aminobutyricacid (GABA), alanine (Ala) were included for major target metabolites. Symmetrical 2D-COSY spectra were successfully acquired. Total 14 COSY cross peaks were observed even though there were parallel/orthogonal noisy peaks induced by water suppression. Except for Cr, all of human brain metabolites produced COSY cross peaks. The spectra of NAA methyl proton at 2.02 ppm and Glu methylene proton ($CH_2(3)$) at 2.11 ppm and Gln methylene proton ($CH_2(3)$) at 2.14 ppm were overlapped in the similar resonance frequency between 2.00 ppm and 2.15 ppm. The present study demonstrated that in vitro 2D-COSY represented the 3-bond connectivity of human brain metabolites by scalar coupling interaction. This study could aid in better understanding the interactions between human brain metabolites in vivo 2D-COSY study. Also it would be helpful to determine the molecular stereochemistry in vivo by using two-dimensional MR spectroscopy.

• Archives of Pharmacal Research
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• v.19 no.4
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• pp.312-316
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• 1996

A series of N-Cbz${alpha}$-aminosucinimides (1), combining common moieties of various anticonvulsants such as N-CO-C-N and cyclic imide in a single molecule, were synthesized from the corresponding (R)- and (S)-N-Cbz-aspartic acid (2). And their in vivo anticonvulsant evaluations in MES and PTZ test were investigated. And also the rotorod test for neurotoxicity was investigated. All the tested compounds (1), except 1c and 1f, showed significant anticonvulsant activities in both MES and PTZ test. And the most active compound among them in MES test was (R)-N-Cbz-${alpha}$-amino-N-methylsuccinimide (1b) $(ED_50/=52.5 mg/kg)$ and (S)-N-Cbz-aminosuccinimide((1d) was most active in PTZ test $(ED_50/=78.1 mg/kg)$. And the $TD_50$ values of the tested compounds were above 117.5 mg/kg. These pharmacological data were comparable to those of currently available anticonvulsants. And also we found that the pharmacological effects were dependent on their N-substituted alkyl chains and their stereochemistry.

• Journal of the Korean Chemical Society
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• v.40 no.11
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• pp.692-698
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• 1996

A synthesis of the oxazole skeleton of discokiolide B, represented by discokiic acid 1, is described. Aldol condensation of 2[2'-(4-phenyl-3-butenyl)]-1,3-oxazole 4-carboxaldehyde(4a) with lithium enolate of methyl propionate provided the discokiic acid methyl ester. The key intermediate 2[2'-(4-phenyl-3-butenyl)]-1,3-oxazole-4-carboxaldehyde (4a) has been synthesized from the rhodium-catalyzed cycloaddition of diazomalonaldehyde with nitrile. The relative stereochemistry of the 3-hydroxy-2-methylpropanoate unit of discokiic acid was assigned on the basis of $^1H$ and $^{13}C$ NMR data.