• 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.

• 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.

• 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.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.2885-2886
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• 2011

• 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.

• 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.30 no.2
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• pp.289-290
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• 2009

• 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.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.61-71
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• 2000

The effect of the treatment with CCFZ, FR-4, and PEG400 from butt end on the dimensional stability and bending properties was examined. Three softwood species such as red pine, Korean white pine and Japanese larch and three hardwood species such as poplar, alder and oak were investigated in this research. Shrinkage of red pine, Korean white pine, poplar, and alder treated with PEG400 decreased. However, there was no significant decrease of shrinkage in Japanese larch and oak. The decrease of shrinkage when moisture content changed from about 20% to 10% was larger than that at any other phase. In regard to the effect of treatment on bending properties, bending MOE and MOR of all specimens treated with PEG400 decreased significantly. Especially in the case of red pine, poplar, and alder treated with PEG400, bending MOR reduced 9%, 14%, and 12%, respectively. Reductions of MOR of the hardwood was also much larger than that of the softwood. However, in all species, treatment with CCFZ and FR-4 did not affect the change of bending MOE and MOR significantly. Comparing the large specimen which also included heartwood with the small specimen which included only treated sapwood, there was a difference in the change of bending MOE and MOR between them. The large specimens of Korean white pine, alder and Poplar, which had a relatively low proportion of sapwood(18~22%), showed the decrease of MOR by 11~13% more than that of small specimens, while red pine, Japanese larch and oak, which had a relatively high proportion of sapwood(35~40%), showed little decrease. It means that bending MOE and MOR of structural wood treated from butt end should be considered in terms of sapwood proportion as well as effect of treated chemicals.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.70-78
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• 2017

The Hwasan wetland vegetation is observed at mountain basin (644~780 m a.s.l.) where had become a potential land for indigenous people since prehistoric period. We phytosociologically investigated old-growth alder (Alnus japonica) forests using the $Z\ddot{u}rich$-Montpellier School's method and analyzed their spatial distribution pattern by actual vegetation map. Species performance was determined by using coverage and r-NCD. Viburnum opulus var. calvescens-Alnus japonica community syntaxonomically belonging to the Alnetea japonicae was first described and composed of three subunits: Salix koreensis subcommunity, typical subcommunity, and Pyrus ussuriensis subcommunity. Present plant community was compared with vicariant syntaxa such as Molinia japonica-Alnus japonica community, Rhamno nipponicae-Alnetum japonicae, and Aceri-Salicetum koreensis. Hwasan's alder forest, an alluvial terrace vegetation type on valley fan in the montane zone, is evaluated as vegetation class [I], which is a sort of benchmark plant community potentially on mountain wetlands in southeastern part of the Korean Peninsula. Simultaneously we suggested an establishment of the national strategy for habitat conservation free from hydrologically radical transform due to military utilization.