• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.61-67
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• 1992

The synthesis of N-benzyloxycarbonyl-L-aspartyl-L-phenylalanine methyl ester(ZAPM), a precursor of aspartame, from N-benzyloxycarbonyl-L-aspartic acid(Z-Asp) and L-phenylalanine methyl ester hydrochloride(L-PM-HCl) was investigated in ethylacetate-MES buffer two-phase system using thermolysin. In organic two-phase system, the degree of spontaneous hydrolysis of L-PM. HCl was significantly reduced with increasing the volume ratio of organic to aqueous phase. Stability of thermolysin in organic two-phase system was found to be higher than that in MES buffer solution. More than 90% of initial enzyme activity was maintained after 10 days of incubation in case that the volume of organic phase was equal to that of buffer phase, while the half life of thermolysin was about 2 days in aqueous buffer solution. The results of partitioning of substrates and product in organic two-phase system showed that the difference in partition coefficients between substrates and product was maximum at pH 5.5. The optimal pH for 2-APM synthesis in organic two-phase system was found to be 5.5-5.8, which is consistent with the value expected from the partition experiments. As the concentration of substrates was increased the conversion yield of Z-APM was increased with concomitant reduction of L-PMqHC1 hydrolysis. In case that the concentration of L-PM-HCl and Z-Asp were 160 mM and 80 mM respectively, the conversion yield of Z-APM reached 90% after 28 hrs of reaction. The yield obtained at different volume ratio of organic phase compares well with the predicted equilibrium constant in biphasic system.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.31-35
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• 2015

Diastereoselective reduction of 2,3-dioxo-4-carboxy-5-(substituted)pyrrolidine 1 by $NaBH_4/AcOH$ and heterogenous hydrogenation were reported. Stereochemical assignment and diastereomeric ratios of the products were determined using $^1H$ NMR and single crystal X-ray analyses. The steric factors of the C-5 substituents of the pyrrolidinone was shown to have an interesting influence on both the yield and diastereoselectivity of the reduced product.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.521-524
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• 2014

Pyronaridine tetraphosphate (1) is a well-known antimalarial drug. However, it required a carefully optimized production process for the manufacture of pyronaridine tetraphosphate. Each step of its manufacturing process was reinvestigated. For the cyclization of 4-chloro-2-(6-methoxy-pyridin-3-yl-amino)-benzoic acid 6 to 7,10-dichloro-2-methoxybenzo[b]-1,5-naphthyridine 5, an improved process was developed to eliminated critical process impurity (BIA). By the redesign of the formation of triphosphate salt, the purity as API grade was increased. Thus, a robust manufacturing process with an acceptable process performance has been developed to produce high quality pyronaridine tetraphosphate.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.840-844
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• 2010

The new MPV type reagent, Al-methanesulfonyldiisobutylalane ($DIBAO_3SCH_3$), has been prepared and its reducing characteristics in the reduction of selected organic compounds containing representative functional groups have been examined in order to find out a new reducing system with high selectivity in organic synthesis. In general, the reagent is extremely mild, showing only reactivity toward aldehydes, ketones and epoxides. The reagent exhibits a unique reducing applicability in organic synthesis. Thus, the reagent can achieve a clean 1,2-reduction of $\alpha,\beta$-unsaturated aldehydes and ketones to produce the corresponding allylic alcohols in 100% purity. In addition, the reagent shows an excellent regioselectivity in the ring-opening reaction of epoxides. Finally, $DIBAO_3SCH_3$ shows a high stereoselectivity in the reduction of cyclic ketones to produce the thermodynamically more stable epimers exclusively.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2883-2886
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• 2009

A simple, highly efficient and environmentally benign method for the synthesis of 3-styrylchromones from 3-formylchromones and 4-nitrophenylacetic acid/4-nitrotolune in the presence of catalytic amount of basic ionic liquid 1-butyl-3-methylimidazolium hydroxide [(bmim)OH] carried out under the influence of microwave irradiation. This method gives remarkable advantages such as, short reaction times, simple work-up procedure and moderate to good yields. The ionic liquid was successfully reused for four cycles without significant loss of activity.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.195-196
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• 2007

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• Journal of the Korean Ceramic Society
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• v.54 no.4
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• pp.272-277
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• 2017

Organic-inorganic hybrid thermoelectric materials have obtained increasing attention because it opens the possibility of enhancing thermoelectric performance by utilizing the low thermal conductivity of organic thermoelectric materials and the high Seebeck coefficient of inorganic thermoelectric materials. Moreover, the organic-inorganic hybrid thermoelectric materials possess numerous advantages, including functional aspects such as flexibility or transparency, low cost raw materials, and simplified fabrication processes, thus, allowing for a wide range of potential applications. In this study, the types and synthesis methods of organic-inorganic thermoelectric hybrid materials were discussed along with the methods used to enhance their thermoelectric properties. As a key factor to maximize the thermoelectric performances of hybrid thermoelectric materials, the nanoengineering to control the nanostructure of the inorganic materials as well as the modification of the organic material structure and doping level are considered, respectively. Meanwhile, the interface between the inorganic and organic phase is also important to develop the hybrid thermoelectric module with excellent reliability and high thermoelectric efficiency in addition to its performance in various electronic devices.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.449-455
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• 1994

In order to obtain the basic data for synthetic studies of bioactive peptide using enzyme, Kyotorphin(analgesic peptide) derivative was synthesized from Ac-Tyr-OH and $Arg-NH_2$ by $\alpha-chymotrysin$ in two phase system(organic phase and aqueous phase). In effect of organic solvent on Kyotorphin derivative synthesis from Ac-Tyr-OH(10 mM) and $Arg-NH_2$ (20 mM), the synthesis in ethyl acetate system of organic solvents was higher than those in other organic solvents (n-butanol, n-hexane, dichloromethane and chloroform). The optimal conditions for the synthesis are as follows: enzyme conc., 10 ${\mu}M;$ reaction pH, 7.0; reaction temp., $35^{\circ}C$ ; the ratio of organic phase volume/aqueous phase volume $(\alpha)$, 15. Under the optimal conditions, the yield was 70.2%, and the reaction achieved to equilibrium after 24 hrs.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.357-365
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• 2010

Combinatorial synthesis, which has been adopted as an efficient method for deriving a leading compound in pharmaceutical chemistry, is recently being applied in various fields along with the rapid development of analysis and examination technology. It is especially attracting much attention as an efficient strategy to secure various potent compounds rapidly in the areas of developing new materials where the relationship between the chemical structure and the property is not revealed. Several reports and reviews have already been published for the combinatorial chemistry and combinatorial synthesis. This report briefly introduces trends in the combinatorial development of new materials and discusses the cases of developing organic luminescent materials.

• Journal of the Korean Chemical Society
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• v.64 no.1
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• pp.7-18
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• 2020

An efficient and facile procedure has been developed for the synthesis of novel bichalcone derivatives (4a, 4b). The key step contains the solvent-free aldol synthesis of bichalcones based on quinones. Bichalcones (4a, 4b) were used as precursors for the synthesis of some interesting heterocyclic compounds like, diazepines (5a, 5b), pyrazolo-pyrimidines (7a, 7b), and pyrazoline derivatives (8a, 8b). Moreover, new thioxopyrimidine derivatives (9a, 9b) were furnished and used as a functionalizing agent to produce the triazole-pyrimidines (11, 12) and the carbonitrile derivative (14). All the synthesized compounds were fully characterized using physical and spectral data like, FT-IR, ¹H NMR, ¹³C NMR, and MS. Bichalcones (4a, 4b) and diazepines (5a, 5b) were screened for their anticonvulsant activity, where compounds (4a, 5a, and 5b) revealed potent anticonvulsant activity compared to diazepam. On the other hand, some of the prepared compounds were screened for their antiproliferative activity and they showed significant cytotoxic effects on most of the cancer cell lines with regard to broad spectrum antitumor activity.