• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.128-131
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• 2017

We explore the inverse electron demand Diels-Alder reactions of tetrazines with various functional groups employing quantum calculations. In general, the rate of inverse electron demand Diels-Alder reaction depends on molecular orbital levels of electron donor and electron acceptor. Likewise, ${\pi}$ orbital of the dienophile and ${\pi}^*$ orbital of the diene is a key factor. In this work, we discuss the case where the energy of diene's ${\pi}^*$ molecular orbital is not the sole governing factor to determine the reaction rate, rather the rate shows strong correlation with the charge density of dienes.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.47-50
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• 2008

The diastereoselectivity of Diels-Alder reactions were studied on the silica surface supported with different concentrations of cerium ion as efficient Lewis acid catalysts under solvent-free conditions. The results showed that the diastereoselectivity of reaction was highly improved in these conditions. The cerium ion was grafted on silica surface by using ion exchange method.

• Bulletin of the Korean Chemical Society
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• v.4 no.5
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• pp.197-200
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• 1983

The Diels-Alder cycloaddition reactions between dienes and allenic ketones were studied theoretically using CNDO/2 method. It was found that the reaction is a neutral electron demand type with matrix element control and the reactivity, the regio- and stereo-selectivities can be correctly predicted based on interaction energies calculated with the 4-center FMO formalism.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.141-152
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• 2017

Inverse electron-demand Diels-Alder reactions (IEDDA) between tetrazine derivatives and strained dienophiles have attracted a lot of attention for the efficient conjugation of biomolecules, polymers, and nanomaterials. Excellent specificity, exceptionally fast reaction rate, and biocompatibility are key features of IEDDA. Therefore, it has also been applied to the development of new labeling methods using several radioisotopes and development of radiotracers to carry out various nuclear imaging as well as therapeutic studies. The purpose of this review is to introduce the reader to the recent advances and applications of IEDDA in the fields of radiochemistry and nuclear medicine.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1679-1684
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• 2011

Interfacial reactions kinetics often differ from kinetics of bulk reactions. Here, we describe how the density change of an immobilized reactant influences the kinetics of interfacial reactions. Self-assembled monolayers (SAMs) of alkanethiolates on gold were used as a model interface and the Diels-Alder reaction between immobilized quinones and soluble cyclopentadiene was used as a model reaction. The kinetic behavior was studied using varying concentrations of quinones. An unusual threshold density of quinones (${\Gamma}_c$ = 5.2-7.2%), at which the pseudo-first order rate constant started to vary as the reaction progressed, was observed. This unexpected kinetic behavior was attributed to the phase-separation phenomena of multi-component SAMs. Additional experiments using more phase-separated two-component SAMs supported this explanation by revealing a significant decrease in ${\Gamma}_c$ values. When the background hydroxyl group was replaced with carboxylic or phosphoric acid groups, ${\Gamma}_c$ was observed at below 1%. Also, more phase-separated thermodynamically controlled SAMs produced a lower critical density (3% < ${\Gamma}_c$ < 4.9%) than that of the less phaseseparated kinetically controlled SAMs (6.5% < ${\Gamma}_c$ < 8.9%).

• Journal of the Korean Chemical Society
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• v.17 no.1
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• pp.1-9
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• 1973

The purpose of this paper is to investigate the mechanism of Diels-Alder reaction by assuming pseudo molecular complex (PMC) which has characters both of ionic and radical bonds. We treated this complex quantum-chemically as an intermediate between the configuration without charge transfer (radical bond character) and the configuration corresponding to the charge transfer from Diene (R) to Dienophile (S) (ionic bond character). The wave function for the complex could be expressed as: ${\psi}_{complex} = {\psi}(R,S) +{ \rho}{\psi}(R^+,S^-)$ where ${\rho}$ is the extent of charge transfer which is a constant to measure the ionic character of PMC. It has been noticed that${\rho}$is related to the difference between Fr + Fr' and Fs + Fs' in free valence (F) when R is united to S through atom r in R to atom s in S and atom r' in R to atom s' in S, That is, ${\rho}{\alpha}$ ${\Delta}F = (Fr + Fr') - (Fs + Fs')$. We have calculated ${\Delta}F$values for more than forty Diels-Alder reactions. The calculated values of ${\Delta}F$ is reversely proportional to the values of Brown's paralocalization energy (Lp) as well as Dewar's differences of delocalization energy$({\Delta}Edeloc.)$ with good linearity. This approach also presents a way of predicting the possibility and the easiness of diene synthesis between any two conjugate compounds. According to the considerations, it could be concluded that Diels-Alder reaction takes place through the united ionic-radical mechanism rather than the separated ionic or radical mechanism.

• Journal of the Korean Chemical Society
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• v.26 no.1
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• pp.7-17
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• 1982

In order to predict substituent and Lewis acid effects on the regiospecificity of the Diels-Alder reaction, and to investigate the competition for the complexation of Lewis acid between diene and dienophile, frontier orbital theory has been applied to thermal and catalyzed Diels-Alder reaction by means of CNDO/2 MO method. It has been found that: (1) Lewis acid coordinated preferentially with diene rather than dienophile when carbonyl oxygen of acetoxy substituted diene had larger negative atomic charges than that of dienophile. (2) Most of the reaction were neutral electron demand type, and hence 4-C, 2-C and quantitative secondary orbital interacion methods were generally in good accord with experiments. (3) Sulfur activated the adjacent terminal carbon atom greatly to increase diene LUMO-dienophile HOMO interaction through vacant-d-orbital participation, and played an important role in controlling regioselectivity of neutral electron demand reaction type.

• Journal of Applied Biological Chemistry
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• v.48 no.2
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• pp.97-100
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• 2005

Chiral dienophile 5 was synthesized from D-glucose by consecutive diisopropylidenation, partial deprotection, diol cleavage, and Wittig reactions. Under thermal conditions, asymmetric Diels-Alder reaction between chiral dienophile and cyclopentadiene gave four possible chiral norbornenes stereoisomers whose absolute configurations were determined through CADD and NMR.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.142-148
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• 1972

The intermolecular orbital theory was applied to the Diels-Alder reaction of naphthalene, phenanthrene and 1,2-benzanthracene with maleic anhydride. The expected positions of thermal addition in the alternant bydrocarbons were in agreement with experiment. It was also possible to explain the relative proportions of two isomeric adducts with the calculated stabilization energies. Comparison of the results with paralocalization energies of Brown gave agood linear correlation.

• Journal of the Korean Magnetic Resonance Society
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• v.8 no.1
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• pp.62-69
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• 2004

Bicyclolactones obtained from the Diels-Alder cycloaddition of 3,5-dibromo-2-pyrone can undergo various palladium catalyzed cross coupling reactions to afford aryl bicyclolactones. The resulting coupled products can be readily converted into various 3-OH cyclohexenes via lactone ring openings, while those bearing dienyl units underwent highly diastereoselective Diels-Alder cycloadditions with selected dienophiles to funish multiply functionalized polycarbocycles. Bromo-bicyclic diene furnished two different diastereomers endo-form (62%) and exo-form (38%) upon cycloadditions with N-Et maleimide (NEM), and their stereochemistries were identified with NMR.