• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.491-500
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• 2004

The Lewis acid-catalyzed reactions of anthrone with a variety of ethylenic substrates under various conditions have been studied. It has been observed that depending on kinds of ethylenic substrates and catalysts, products were varied. In particular, the $ZnCl_2$-catalyzed reaction of anthrone with ${\alpha},{\beta}$ -unsaturated ester gave bridged compounds 3 (Diels-Alder adduct type) and mono-Michael adduct 4 exclusively, while the base-catalyzed reaction gave 10,10-bis-Michael adduct as a major product independent of the amount of ethylenic substrate and base. Bridged compounds 3 were easily converted to the corresponding mono-Michael adduct 4 by a catalytic amount of base. Further Michael reaction of mono-Michael adducts with different ethylenic substrates in the presence of a catalytic amount of alkoxide gave unsymmetrical 10,10-bis Michael adducts in good or moderate yields.

• 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.29 no.10
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• pp.1977-1982
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• 2008

Novel bicyclo[3.1.0]hexanyl purine nucleoside analogues were synthesized as potential antiherpetic agents via a bicyclo[3.1.0]hexanol (${\pm}$)-8, which was prepared using a highly efficient carbenoid cycloaddition reaction. A highly diastereoselective reduction of ketone and a Mitsunobu reaction for the condensation of glycosyl donor (${\pm}$)-12 with 6-chloropurine were employed.

• Carbon letters
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• v.10 no.4
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• pp.325-328
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• 2009

This cycloaddition of [70]fullerene with methyl azidoacetate in benzene under ultrasonic irradiated condition afforded the closed [5,6]-bridged aziridino[70]fullerene derivative, which was unusual product of cycloaddition to the 5,6-junction of fullerene. Its structure was determined by FAB-MS, UV-vis, $^1H-$ and $^{13}C$-NMR spectral data. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films were self-assembled using the layer-by-layer method on the reactive of glass slides functionalized with 3-mercaptopropyl trimethoxysilane. The functionalized glass slides were alternately soaked in the solution containing closed the [5,6]-bridged aziridino[70]fullerene and 4-aminothiophenoxide/hexanethiolate-protected gold nanoparticles. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films have grown up to 5 layers depending on the immersion time. The self-assembled nanoparticle multilayer films were characterized using UV-vis spectroscopy showed that the surface plasmon band of gold at 527 nm gradually became more evident as successive layers were added to the films.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.591-596
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• 2003

Aminothienopyridazines 1a, b and aminothienocoumarin 2 condensed with DMFDMA to yield amidines 3a, b and 4. These compounds reacted with N-phenylmaleimide to yield 9 and 10. On the other hand reacting 3a, b, 4, 18, 19 and 20 with maleic anhydride afforded only the formylated derivatives 5a, b, 6, 21, 22 and 23 respectively. The reaction of 3a, b with diethyl fumarate afforded 11, formed most likely via hydrolysis of the amidine 14 during working up the reaction mixture. Irradiation of N-phenylmaleimide in microwave oven afforded [2+2] and [2+2+2] cycloaddition product.

• 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.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.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.395-398
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• 1992

In order to study the influence of a 6'-methyl group in ring C of griseofulvin ${\underline{(1)}}$ on the fungicidal activity, 6'-methyl group was replaced with a larger phenyl group as $({\pm})-6'-phenylgriseofulvin$ ${\underline{(3)}}$, $({\pm})-6'-epiphenylgriseofulvin$ ${\underline{(4)}}$, synthesized by a Diels-Alder cycloaddition. Their biological activities were examined against Botrytis allii (IFO 9430) and B. cinerea (AHU 9573). $({\pm})-6'-Phenylgriseofulvin $ ${\underline{(3)}}$ showed high activity in $25\;{\mu}g/disc$.

• Elastomers and Composites
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• v.45 no.4
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• pp.286-290
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• 2010

Liquid-crystalline (LC) monomer, which was functionalized with a coumarin group on their extremity, was synthesized by UV light irradiation in their LC phases. LC monomer was converted into the dimers by the cycloaddition reaction of the coumarin group, and the LC phases were maintained after photodimerization reaction. The dimers showed LC phases in the wider temperature range than those of the corresponding monomer. Structures of the compound were identified by FT IR and $^1H$ NMR spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry (DSC), gel permeating chromatography (GPC) and polarized optical microscopy (POM). From optical polarizing microscopy, the prepared polymer shows enantiotropic liquid crystallinity with smectic and nematic textures.

• Clean Technology
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• v.14 no.3
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• pp.166-170
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• 2008

In this study, imidazolium salt ionic liquid on amorphous silica was prepared and its catalytic performance in the cycloaddition of $CO_2$ with allyl glycidyl ether (AGE) to produce heterocyclic carbonate was investigated. The ionic liquid was generated on chloropropyl functionalized silica through the immobilization of imidazole. The prepared catalyst was characterized using a number of instrumental analysis including XRD, BET, $^{29}Si$ MAS-NMR and SEM. $^{29}Si$ MAS-NMR showed that the ionic liquid formed adduct with the chloropropyl groups attached to the silica surface. The immobilized ionic liquid showed very good catalytic activity for the cycloaddition of $CO_2$ with AGE, showing 55-61% of AGE conversion with over 85% of the carbonate selectivity at $80-120^{\circ}C$. Its AGE conversion and selectivity to the carbonate were even higher than the homogeneous analog, 1-n-butyl-3-methyl imidazolium bromide (BMImBr).