• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1459-1462
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• 2002

The kinetics of the addition of X-substituted benzylamines (BA) to Y-substituted Benzylideneacetylacetones (BAA) have been investigated in acetonitrile at $25.0^{\circ}C$. The reaction is studied under pseudo-first-order conditions by keeping a large excess of BA over BAA. The addition of BA to BAA occurs in a single step in which the addition of BA to $C_\alpha$ of BAA and proton transfer from BA to $C_\beta$ of BAA take place concurrently with a four-membered cyclic transition state structure. The magnitude of the Hammett ($p_X$) and Bronsted ($\beta_x$) coefficients are rather small suggesting an early tansition state (TS). The sign and magnitude of the cross-interaction constant, $p_{XY}$ (= -0.49), is comparatible to those found in the normal bond formation processes in the $S_N2$ and addition reactions. The normal kinetic isotope effect ($K_H/K_D$ > 1.0) and relatively low $\Delta$H^{${\neq}$}$ and large negative $\Delta$S^{${\neq}$}$ values are also consistent with the mechanism proposed.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.976-980
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• 2006

The synthesis of 4'-phenyl and 1'-methyl doubly branched carbocyclic nucleoside was accomplished from 2-hydroxy acetophenone. The 4'-phenyl group was installed via a [3,3]-sigmatropic rearrangement reaction, and the carbonyl addition of methylmagnesium bromide was used to introduce the 1'-methyl group. Cyclization of divinyl 9 was performed using $2^{nd}$ generation Grubbs catalyst. The coupling of cyclopentenol 12$\alpha$ with 6-chloropurine by Mitsunobu reaction and desilylation was used to synthesize the target nucleoside 15.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.56.5-56
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• 2001

In the three axis control of satellite by using reaction wheel and gyro, a reaction wheel produces the control torque by the wheel speed or momentum, and a gyro carries out measuring of the attitude angle and the attitude angular velocity In this study, dynamic modelling of the Low Earth Orbit (LEO) is consisted of the one from the rotational motion of the satellite with the basic rigid body and a flexible body model, and the gyro in addition to the reaction wheel model. The results obtained by the robust controller are compared with those of the PI (Proportional and Integration) controller which is commonly used for the stabilizing satellite.

• Journal of Photoscience
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• v.12 no.3
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• pp.185-186
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• 2005

The electronic structure of photoskinsensitizing psoralens has been investigated by the ab initio calculations. The photocycloaddition reaction of 8-methoxypsoralen with thymine is studied as a model for the photosensitizing reaction of psoralen with DNA bases. The photocycloadduct was inferred to be a C4-cycloaddition product with the stereochemistry of Syn, H-H, Syn, H-T formed through [2+2] addition reaction between the 3,4-double bonds of 8-methoxypsoralen and 5,6-double bond of thymine base.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3382-3384
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• 2010

A new synthetic route to ($\pm$)-aspidospermidine was devised, starting from the cycloadduct of 3-ethyl-5-bromo-2-pyrone with vinyl sulfide through a tandem conjugate addition-alkylation sequence. The requisite 3-ethyl-5-bromo-2-pyrone was prepared via the C3-selective Pd-catalyzed coupling reaction with $Et_3Al$-dimethylaminoethanol complex.

• Archives of Pharmacal Research
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• v.16 no.3
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• pp.205-208
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• 1993

($\pm$)-Myodesmone was synthesized, starting from 2-cyclopentenone. The key reaction involved $\alpha$-dimethoxymethylation of 2-cyclopentenone and organocopper conjugate addition reaction.

• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.346-351
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• 2019

Mannich-type reactions of cyclic N-sulfimines with 2-trimethylsiloxyfuran and pyrazolin-5-one have been developed using phosphoric acid (PA) as an organocatalyst. 2-Trimethylsiloxyfuran underwent a vinylogous Mannich-type reaction with cyclic N-sulfimines in the presence of the PA catalyst to give sulfamidate ${\gamma}$-butenolides in good yields and with high diastereoselectivities (up to 90% yield and 7:1 dr). In addition, the reaction between pyrazolin-5-one and a diverse range of cyclic N-sulfimines provided access to sulfamidates in good to high yields (up to 94% yield).

• Journal of the Korean Applied Science and Technology
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• v.16 no.2
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• pp.171-177
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• 1999

The objectives of this study is to investigate the optimum reaction conditions and to identify the product formula in the synthesis of a silicone/acrylic resin that curing in moisture at room temperature. By the addition polymerization of monomers, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyltrimethoxysilane. a quarter polymer was obtained. Among various initiators investigated in this study, 2.2'-azobisisobutyronitrille was found to be the most suitable initiator. The optimum reaction conditions found in this study are 70 wt% of initial solvent amount, 120 minutes of dropping time, 3 times of initiator addition, $82{\sim}105^{\circ}C$ of reaction temperature, and 8 hrs of reaction time. Also, number average molecular weight of $11700{\sim}33100$ and molecular weight distribution of $1.81{\sim}3.44$ were obtained.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.345-349
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• 2006

Conversion of DME (dimethyl ether) or methanol to light olefins (ethylene, propylene, butenes) over SAPO-34 were systematically studied, where it was observed that DME was dehydrated to light olefins and partially converted to by-products such as CO and $CO_2$ at various reaction temperatures on the time-on-stream. SAPO-34 catalyst during the DTO (dimetyl ether-to-olefins) reaction was significantly deactivated compared with MTO (methanol-toolefins) reaction. By addition of water to the reaction feed, the yield to light olefins was not only increased, but the life time of the catalyst was also prolonged by the suppression of the coke formation by steam.

• Natural Product Sciences
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• v.16 no.3
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• pp.185-191
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• 2010

Mast cell-mediated allergic disease is involved in many diseases such as anaphylaxis, asthma and atopic dermatitis. The discovery of drugs for the treatment of allergic disease is an important subject in human health. In the present study, the effect of water extract of Gleditsiae Spina (WGS) (Leguminosae), on compound 48/80-induced systemic allergic reaction, anti-DNP IgE antibody-induced local allergic reaction, and histamine release from human mast cell line (HMC-1) cells were studied. In addition, the effect of WGS on phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187 (A23187)-induced gene expression and secretion of pro-inflammatory cytokines were investigated using HMC-1 cells. WGS was anally administered to mice for high and fast absorption. WGS inhibited compound 48/80-induced systemic allergic reaction. WGS dose-dependently decreased the IgE-mediated passive cutaneous anaphylaxis. WGS reduced histamine release from HMC-1 cells. In addition, WGS decreased the gene expression and secretion of pro-inflammatory cytokines in PMA plus A23187-stimulated HMC-1 cells. These findings provide evidence that WGS could be a candidate as an antiallergic agent.