• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.354-362
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• 2003

A strategy for synthesis of the furan-fused tetracyclic system of xestoquinone was explored through a model study. Using 3-butyn-1-ol as a starting material, 5-iodo-1-methoxymethoxy pentyne (5) was prepared in 5 steps. Reaction of ethyl 2-phenylpropanoate with 5 gave ethyl 7-methoxymethoxy-2-methyl-2-phenyl-5-heptynoate (6) in 88% yield, and then methyl 9-oxo-4-methyl-4-phenyl-2,7-nonadiynoate (13), the key intermediate, was synthesized in 6 steps from the ester 6. Intramolecular cycloaddition reaction of 13 afforded isobenzofuran 14 in 5% yield, which was converted to the tetracyclic structure 15 in the presence of Lewis acid.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.139-145
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• 2005

Artificial neural networks (ANNs), for a first time, were successfully developed for the modeling and prediction of solvent effects on rate constant of [2+2] cycloaddition reaction of diethyl azodicarboxylate with ethyl vinyl ether in various solvents with diverse chemical structures using quantitative structure-activity relationship. The most positive charge of hydrogen atom (q$^+$), dipole moment ($\mu$), the Hildebrand solubility parameter (${\delta}_H^2$) and total charges in molecule (q$_t$) are inputs and output of ANN is log k$_2$ . For evaluation of the predictive power of the generated ANN, the optimized network with 68 various solvents as training set was used to predict log k$_2$ of the reaction in 16 solvents in the prediction set. The results obtained using ANN was compared with the experimental values as well as with those obtained using multi-parameter linear regression (MLR) model and showed superiority of the ANN model over the regression model. Mean square error (MSE) of 0.0806 for the prediction set by MLR model should be compared with the value of 0.0275 for ANN model. These improvements are due to the fact that the reaction rate constant shows non-linear correlations with the descriptors.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.1021-1022
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• 2002

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.647-650
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• 2001

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4079-4083
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• 2012

The mechanism of the cycloaddition reaction between singlet state dichlorosilylene germylidene ($Cl_2Si=Ge:$) and acetone has been investigated with B3LYP/6-$31G^*$ and B3LYP/6-$31G^{**}$ method, from the potential energy profile, we predict that the reaction has one dominant reaction pathway. The presented rule of the reaction is that the two reactants firstly form a Si-heterocyclic four-membered ring germylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge atom in the Si-heterocyclic four-membered ring germylene and the ${\pi}$ orbital of acetone forming a ${\pi}{\rightarrow}p$ donor-acceptor bond, the Si-heterocyclic four-membered ring germylene further combines with acetone to form an intermediate. Because the Ge atom in the intermediate hybridizes to an $sp^3$ hybrid orbital after the transition state, then, the intermediate isomerizes to spiro-heterocyclic ring compound involving Si and Ge (P4) via a transition state.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1790-1794
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• 2005

Fréchet-type dendritic benzyl azides were efficiently synthesized using 5-(azidomethyl)-1,3-dihydroxybenzene as an azide focal point functionalized unit by adding a generation to the existing dendron and applied for the construction of dendrimers containing 1,2,3-triazole rings as connectors via click chemistry with a tripodal acetylene core.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.736-742
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• 2015

The effect of pressure on 1,3-dipolar cycloaddtion has been studied by means of FT-IR and NMR spectroscopy. Pressure accelerates 1,3-dipolar cycloaddition without solvent or catalyst. This simple and inexpensive method eliminates the need for work-up or purification. The method is expected to be applied to the synthesis of binders for solid rocket propellants.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.137-142
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• 2012

The convergent synthetic strategy for the emissive dendrimers having the chromophore at core via the coppercatalyzed 1,3-dipolar cycloaddition reaction between alkyne and azide was described. 2,7-Diazido-9,9-dioctyl-9H-fluorene, designed to serve as the core in dendrimer, was stitched with the alkyne-functionalized Frechettype and PAMAM dendrons by the click chemistry leading to the formation of the corresponding fluorescent dendrimers in high yields. The preliminary photoluminescence studies indicated that 2,7-diazido-9,9-dioctyl-9H-fluorene showed no fluorescence due to the quenching effect from the electron-rich ${\alpha}$-nitrogen of the azido group but the dendrimers fluoresced due to the elimination of the quenching through the formation of the triazole ring.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.178-188
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• 1972

Diethyl itaconate was found to react tetrafluoroethylene, trifluorochloroethylene, and 1,1-difluoro-2,2-dichloroethylene quite rendily at $180^{\circ}C$ to form 1-carboxy-2,2,3,3,-tetrahalo-cyclobutane ethanoic acid derivatives ${C{\underline{X_2-CF_2-CH_2-}}C-(COOEt)-CH_2COOEt$, where X is Cl or F). Diethylcitraconate failed to yeild any cycloaddition products. The Physical and Chemical properties of the above esters and their dericatives are characterized and compared with other similar ring compounds.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1085-1086
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• 2007