• 대한화장품학회지
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• 제30권4호
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• pp.491-497
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• 2004

일련의 Alkyl-3,4-dihydroxybenzoate (A)와 N-Alkyl-3,4-dihydroxybenzamide (B) 유도체들의 치환기($R_l$ 및 $R_2$) 변화에 따른 멜라닌생성 저해활성 관계들을 HQSAR 방법으로 분석하였다. 멜라닌생성 저해활성에 관하여 유도된 HQSAR 모델은 매우 양호한 예측성(cross-validated $r^2_{cv.},\;q^2=0.674)$과 적합성(non-cross-validated, $r^2_{ncv}=0.936)$을 나타내었다. 멜라닌생성 저해활성과 가수분해 반응성은 공히, (A)가 (B)보다 컸으며(A$R_l$-치환기가 $R_2$-치환기보다 저해활성에 의존적인 경향을 나타내었다$(R_l>R_2)$. 또한, 경계분자궤도(FMO) 이론에 따라 가수분해 반응은 (A), (B)의 LUMO와 물분자의 HOMO 사이에 강한 상호작용으로 orbital-control 반응인 친핵성 첨가-제거반응$(Ad_{N-E})$이 주로 일어나는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.2911-2915
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• 2011

Efficient synthetic method for the preparation of ethyl 2-aryl-2,3-alkadienoates through Pd-catalyzed selective allenyl cross-coupling reactions of aryl iodides with organoindiums generated in situ from indium and ethyl 4-bromo-2-alkynoate was developed. The cyclization reaction of ethyl 2-aryl-2,3-alkadienoates catalyzed by $AuCl_3$ and AgOTf in the presence of AcOH or TfOH produced various ${\alpha}$-aryl ${\gamma}$-butenolides or ${\gamma}$-substituted ${\alpha}$-aryl ${\gamma}$-butenolides.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1754-1758
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• 2014

The nucleophilic substitution reactions of bis(Y-aryl) chlorothiophosphates (1) with X-pyridines are investigated kinetically in acetonitrile at $35.0^{\circ}C$. The free energy relationships with both X and Y are biphasic concave upwards with a break point at X = 3-Ph and Y = H, respectively. The sign of cross-interaction constants (CICs; ${\rho}_{XY}$) is positive with all X and Y. Proposed mechanism is a stepwise process with a rate-limiting leaving group departure from the intermediate with all X and Y. The kinetic results of 1 are compared with those of Y-aryl phenyl chlorothiophosphates (2). In the case of Y = electron-withdrawing groups, the cross-interaction between Y and Y, due to additional substituent Y, is significant enough to change the sign of ${\rho}_{XY}$ from negative with 2 to positive with 1, indicative of the change of mechanism from a rate-limiting bond formation to bond breaking.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3749-3754
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• 2010

Various terphenyl and quaterphenyl derivatives were prepared by the Ni-NHC catalyzed cross coupling of the corresponding biphenyl- and terphenyl-sulfonates with arylmagnesium bromides. The reactions proceeded rapidly via a nucleophilic aromatic substitution of the alkoxysulfonyl moieties by the aryl nucleophiles to afford high yields within just 1.5 h at room temperature in spite of the low reactivity of the sulfur electrophiles.

• 대한화학회지
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• 제57권3호
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• pp.361-364
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• 2013

A modified synthetic approach to the synthesis of heterocyclic food mutagens, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PHIP) and 2-amino-1,6-dimethylimidazo[4,5-b]pyridine (DMIP) is reported. This route highlights an optimized palladium catalysed Buchwald cross-coupling of 2-halo-1-methyl-imidazo[4,5-b]pyridine with benzophenoneimine followed by acidic hydrolysis to yield compound 7. Using finely tailored conditions, Suzuki cross-coupling reactions with highly efficient catalytic systems were performed as the final step on 8 to introduce the aryl group and methyl group on the heterocyclic core.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.286-290
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• 2016

Background: Activation of air and water in the electron linear accelerator for medical use has not been considered severely. By the new Japanese regulation for protection of radiation hazard, it became indispensable to evaluate of activation of air and water in the accelerator room. The measurement of induced activity in air and water components in the electron energy region of 10 to 20 MeV is very difficult, because this energy region is close to the threshold energy region of photonuclear reactions. Then, we measured the photonuclear reaction yields of $^{13}N$, $^{15}O$, and $^{11}C$ by using the electron linear accelerator. Obtained data were compared with the data calculated by the Monte Carlo method. Materials and Methods: An activation experiment was performed at the Research Center for Electron Photon Science, Tohoku University. Highly purified $SiO_2$, $Si_3N_4$, and carbon disks were irradiated for 10 minutes by bremsstrahlung converted by a tungsten plate. Induced activity from C, N, and O was obtained. Monte Carlo calculation was performed using MCNP5 and AERY (DCHAIN-SP) to simulate the experimental condition. Cross section data were adopted the KAERI dataset. Results and Discussion: In our experiment in hospital, calculated values were not agreed with experimental values. It might be three possible reasons as the cause of this deference, such as irradiation energy, calculation procedure and cross section data. Obtained data of this work, calculated and experimental values were good agreement with each other within one order. In this work, we used KAERI dataset of photonuclear reaction instead of JENDL. Therefore, it was found that the photonuclear cross section data of light elements are most important for yield calculation in these reactions. Conclusion: Further improvement for calculation using a new dataset JENDL/PD-2015 and considering electron energy spreading will be needed.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.203-206
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• 2004

The kinetics of reactions between Z-aryl thiophene-2-carbodithioates and X-pyridines in acetonitrile at 60.0 $^{\circ}C$ have been investigated. The Bronsted plots obtained for the pyridinolysis of aryl thiophene-2-carbodithioates are curved, with the center of curvature at $pK_a$ ~ 5.2 ($pK_a^{\circ}$). The Bronsted plots for these nucleophilic reactions show a change in slope from a large ( ${\beta}_X{\cong}$0.78-0.87) to a small ( ${\beta}_X{\cong}$0.33-0.35) value, which can be attributed to a change in the rate-determining step from breakdown to formation of a zwitterionic tetrahedral intermediate in the reaction path as the basicity of the pyridine nucleophile increases. A clear-cut change in the crossinteraction constants, ${\rho}_{XZ}$, from +0.92 to -0.23 supports the proposed mechanistic change. The breakpoint at $pK_a$ = 5.2 for R = thiophene ring in the present work is in agreement with those for the pyridinolysis of R = Me and 2-furyl, and attests to the insignificant effects of acyl group, R, on the breakpoint.

• 대한화학회지
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• 제32권5호
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• pp.416-421
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• 1988

메탄올-아세토니트릴 혼합 용매계에서 할로겐화 벤질(파라 치환된 브롬화 벤질과 요오드화 벤질)과 피리딘 사이의 친핵성 치환반응을 속도론적으로 연구하여 반응메카니즘을 밝혔다. 치환기 상호 작용 계수 ${\rho}_{XY}$값으로 부터 할로겐화 벤질과 피리딘 사이의 반응은 전이 상태에서 dissociative S$_N$2 메카니즘으로 진행되고 있음을 알 수 있었다. Hammett ${\rho}$(${\rho}_X$, ${\rho}_Y$) 값, Br${\o}$nsted ${\beta}_N$값, 분광 용매화 관계식의 계수 a, s 및 a/s 값을 이용하여 비교하였다. PES 모형과 QM 모형의 분석결과 QM 모형 해석에 잘 적용 됨을 알수 있었다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권4호
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• pp.1637-1641
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• 2016

Oxaliplatin, a third generation novel platinum compound is the most effective first line chemotherapeutic agent for colorectal cancer (CRC) in combination with 5FU and leucovorin. It is indicated for pancreatic, gastric and testicular cancers combined with bevacuzimab, capecitabine, irinotecan and other cytotoxic agents. However, moderate to severe hypersensitivity reactions (HSR) during or after oxaliplatin infusion usually require cessation of chemotherapy or substitution of the key therapeutic drug which largely interferes with improved patient prognosis. This mini- review showcases recent and accepted opinions/approaches in oxaliplatin induced HSR management. Physicians and oncologists have varying attitudes regarding the decision to rechallenge the patient after an HSR experience, efficacy of desensitization protocols, effectiveness and selection of drugs for premedication and possibilities of cross sensitivity to other platinum agents (e.g. carboplatin). A brief insight into underlying molecular mechanisms and clinical manifestations of oxaliplatin induced HSR is offered. We have also discussed the management of oxaliplatin induced HSR and risk stratification for a successful and complete chemotherapeutic plan.

• Nuclear Engineering and Technology
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• 제42권5호
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• pp.600-607
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• 2010

Rhenium-186, having a half-life of 90.64 h, is an important radionuclide, used in metabolic radiotherapy and radio immunotherapy. $^{186}Re$ hydroxyethylidene diphosphonate (HEDP) is a new compound used for the palliation of painful skeletal metastases. Its production is achieved via charged-particle-induced reactions; the data are available in EXFOR library. For the work discussed in this paper, production of $^{186}Re$ was done via $^{nat}W(p,n)^{186}Re$ nuclear reaction. Pellets of $^{nat}W$ were used as targets and were irradiated with 15, 17.5, 20, 22.5, 25 MeV proton beams at 5 ${\mu}A$ current. The radiochemical separation was performed by the ion exchange chromatography method. The production yield achieved at 25 MeV was 1.91 $MBq{\cdot}{\mu}A^{-1}{\cdot}h^{-1}$. Excitation functions for the $^{186}Re$ radionuclide, via $^{186}W(p,n)^{186}Re$ and $^{186}W(d,2n)^{186}Re$ reactions were calculated by ALICE-ASH and TALYS-1.0 codes to validate and fit the experimental data and to obtain a recommended set of data for $^{186}W(p,n)^{186}Re$ reaction. Required thickness of the targets was obtained by SRIM code for each reaction.