• Journal of the Korean Chemical Society
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• v.39 no.7
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• pp.493-500
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• 1995

The geometry optimization of oxazole, relevant to the binding of lexitropsin that contains this ring to the base pair (G-C sequence) of minor groove of DNA, is performed with the aid of MM+ and ab initio (Hartree-Fock) calculations. The proton affinity and electronic structure are calculated at the 6-31G and $6-31G^{\ast}$ level for the optimized geometry. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate the substituent effect on the proton affinities of oxazoles. It is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it. This result can be explained with atomic charge and electron density at oxygen of substituted oxazoles.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.7-13
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• 2007

The oxazole plays an important role in the binding of lexitropsin to the guanine-cytosine base pair from minor groove of DNA. The geometry optimization is performed with DFT calculations for the two possible conformations of the protonated oxazole. The proton affinities are calculated at B3LYP level of theory with 6-31G* basis set for the optimized geometry. It is found that the proton affinites of the conformations in which the oxazole nitrogen is the protonation center are greater than that of the conformations in which the oxazole oxygen is the protonation center. This result is in good agreement with molecular electrostatic potential (MEP) contour map. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate substitutent effect on the proton affinity at the hydrogen bonding site of the oxazoles. it is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.133-136
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• 2003

A series of oxazolone derivatives (4a-n) have been synthesized as a potential antibacterial agent. Titled compounds have been prepared by the condensation of aryloxy acetyl-amino-acetic acid with aldehyde in presence of ethanol, acetic anhydride and sodium acetate. The structures of the new compounds were established on the basis of $^1H$ NMR and IR spectral data.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.177-181
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• 2004

1,2,4-Triazoles, pyrazolones and 1,3,4-oxadiazoles have been synthesized from substituted hydrazide using various solid supports under microwave irradiation (MWI). The results obtained highlight the versatility of the solid supports. All synthesized compounds were screened for their antifungal activity against A. niger and A. flavus and were found to possess good activity.

• Proceedings of the Membrane Society of Korea Conference
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• 2005.05a
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• pp.157-160
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• 2005

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.227-230
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• 2005

• 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.

• YAKHAK HOEJI
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• v.38 no.5
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• pp.504-510
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• 1994

A facile synthesis of 2-aryl-5-benzoxazolepropionic acid derivatives(1 0a-d), which are potent antiinflammatory agent, is reported. Methyl ${\alpha}$-(p-hydroxyphenyl)propionate(5) was prepared from Friedel-Crafts reaction of isopropoxy benzene with methyl ${\alpha}$-chloro-${\alpha}$-(methylthio) acetate(1), followed by desulfurization, methylation and clevage of ether bond. Compounds(10a-d) were made from(5) by a sequence of nitration, reduction, formation of benzoxazole ring, and hydrolysis in good yields, respectively.

• Polymer(Korea)
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• v.29 no.5
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• pp.493-500
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• 2005

Polyhydroxyamides(PHAs) having poly(ethylene glycol)methyl ether (MPEG) and/or dimethylphenoxy pendant groups were synthesized by solution polycondensation at low temperature. The inherent viscosities of the PHAs measured at $35^{\circ}C$ in DMAC or DMAc/LiCl solution were in the range of $0.51\~2.31dL/g$. This precursor polymers were studied by FT-IR, $1H-NMR$, DSC, and TGA. Solubility of the precursors with higher MPEG unit was increased, especially the polymer having MPEG $(M_n=1100)$ was soluble or partially soluble in ethanol, methanol, and water as well as aprotic solvents, but the PBOs were nearly insoluble in a variety of solvents. PHAs were converted to polybenzoxazoles (PBOs) by thermal cyclization reaction with heat of endotherm. In case of the precursors having MPEG nit, the precursor polymers with a higher $M_n$ were fully cyclized at a lower temperature than one with a lower $M_n$.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.53-58
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• 2018

Since the scaling-down of IC devices has been reached to their physical limitations, several innovative packaging technologies such as 3D packaging, embedded packaging, and fan-out wafer level packaging (FOWLP) are actively studied. In this study the fabrication of organic-inorganic dielectric material was evaluated for the use of multi-structured redistribution layers (RDL) in FOWLP. Compared to current organic dielectrics such as PI or PBO an organic-inorganic hybrid dielectric called polysilsesquioxane (PSSQ) can improve mechanical, thermal, and electrical stabilities. polysilsesquioxane has also an excellent advantage of simultaneous curing and patterning through UV exposure. The polysilsesquioxane samples were fabricated by spin-coating on 6-inch Si wafer followed by pre-baking and UV exposure. With the 10 minutes of UV exposure polysilsesquioxane was fully cured and showed $2{\mu}m$ line-pattern formation. And the dielectric constant of cured polysilsesquioxane dielectrics was ranged from 2.0 to 2.4. It has been demonstrated that polysilsesquioxane dielectric can be patterned and cured by UV exposure alone without a high temperature curing process.