• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.392-397
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• 1991

A stereocontrolled synthesis of (${\pm}$)-isocomene (1) via selective monoketalization of tricyclo[6.3.0.$0^{1.5}$]undeca-4,7-dione(13) was reported. Grignard reaction of bicyclic enone 10, which was prepared from 2-methyl-1,3-cyclopentadione, gave the 1,4-addition product 11. The subsequent aldol condensation product 12 was converted to mesyl derivative 13. Transformation from 13 to the desired product 19 was achieved by a series of reactions, i.e., the selective monoketalization at C-4 carbonyl group, the elimination of a mesyl group, Birch alkylation, methylation at C-6, the reduction of carbonyl group, the dehydration of alcohol 18, and hydrolysis of the ketal group.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.4
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• pp.123-128
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• 2020

All plants in natural ecosystems are living in symbiosis with endophytes. Recently, there has been an increasing interest in endophytes since these organisms can interact with the hosts and produce various structurally or biologically interesting molecules. This study aimed to identify these molecules from endophytes. Chemical investigation of Climacium dendroides-derived fungus Talaromyces sp. resulted in the isolation of two diphenyl ether derivatives, purpactin A (1) and penicillide (2), and two steroids, dankasterone A (3) and calvasterol B (4). The structures of the compounds were identified via extensive spectroscopic and spectrometric methods. Four compounds did not show any antioxidative activities in the on-line antioxidant activity screening system.

• Natural Product Sciences
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• v.15 no.3
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• pp.121-124
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• 2009

Phytochemical investigation of the aerial parts of Lonicera etrusca resulted in the isolation of three iridoids including two aglycones, loganin aglycone (log-1) (1) and lonicerin (log-2) (2), and the known common glycoside loganin (4). The study also afforded a coumarin derivative, 7-hydroxycoumarin (3), and a flavonoid glycoside, luteolin-7-O-$\beta$-D-glucoside (5). The structures were determined utilizing physical, chemical and spectral methods.

• East Asian mathematical journal
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• v.24 no.4
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• pp.347-358
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• 2008

In this paper we investigate integral means inequalities for the integral operators $Q_{\lambda}^{\mu}$ and $P_{\lambda}^{\mu}$ applied to suitably normalized analytic functions. Further, we obtain some neighborhood and inclusion properties for a class of functions $G{\alpha}({\phi}, {\psi})$ (defined below). Several corollaries exhibiting the applications of the main results are considered in the concluding section.

• Natural Product Sciences
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• v.9 no.4
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• pp.241-244
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• 2003

A new (2) and a known (1) acylated taurine derivatives were isolated from MeOH extract of the starfish Certonardoa semiregularis. Another new acylated taurine derivative (3) was isolated from the MeOH extract of the sponge Erylus nobilis. The structures were determined on the basis of spectral analysis.

• Natural Product Sciences
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• v.5 no.3
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• pp.134-137
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• 1999

The chloroform extract of Pulicaria gnaphalodes yielded flavonoids (1-2), sesquiterpenoid (3), sterol (4), benzoic acid derivative (5) and fatty acids (6-7). Their structures were elucidated with the aid of NMR spectroscopy. The described compounds have not been reported so far from this source.

• Archives of Pharmacal Research
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• v.14 no.4
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• pp.379-384
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• 1991

The Knoevenagal reaction of malononitrile and acetylacetone gave the acyclic product 3 which was separated in a good yield and identified. The reactivity of 3 towards some chemical reagents is studied. Thus, the reaction of 3 with aromatic aldehydes, hydrazines and cyanomethylene derivatives gave products 6-12. Reaction of 3 with benzenediazonium chloride gave the primidine derivative 14.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1433-1436
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• 1999

The 2-(2,4-dimethoxyphenyl)-4-MDO (2) underwent polymerization with ring opening as well as cyclization reaction in the presence of various cationic catalysts such as boron trifluoride, trifluoromethanesulfonic acid, p-toluenesulfonic acid, hydrochloric acid and trifluoroacetic acid. They afforded a mixture of the ring-opened poly(keto ether) and 3(2H)-dihydrofuranone derivative. Both the methylene group and oxygen atom of 1,3-dioxolane ring were participated in the reaction with cationic catalyst. The contents of the polymer and cyclization product were variable according to the acid strength of the cationic catalysts.

• Journal of the Korean Applied Science and Technology
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• v.11 no.1
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• pp.53-60
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• 1994

The Synthesis of azobenzene containing long chain fatty acid and poly vinyl alcohol by esterification reaction($C_{n}-Azo-PVA$) was optimized, starting from P-(P'-hydroxy phenyl azo)-benzoic acid and the product of reaction containing azobenzene chromophores was investigated by ultraviolet spectrophotometery in toluene solvent at room temperature. In addition, UV absorption spectra of Langmmuir Blodggett (LB) film deposited on quartz plate have been measured and the structure of these compounds were ascertained by means of Ultraviolet and FT-IR. Recrystallization of reaction product in the solvent results the experimental yield obtained about 22.27% P-(P'-octadecyloxy phenyl azo)-benzoic acid-poly vinyl alcohol. Long chain azobenzene derivative-poly vinyl alcohols are induced phtoisomerization by u, v, and visible light irradiation. The LB film of azobenzene containing long chain fatty acids($C_{18}-Azo-PVA$) are possible of being applied to functional molecular devices such as photomemory and light switching.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1478-1481
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• 2012

Geldanamycin (GM) and its analogs are important anticancer agents that inhibit heat shock protein (Hsp) 90, which is a major chaperone protein in cancer cells. Accordingly, based on interest in obtaining novel natural GM derivatives, the potential of Streptomyces hygroscopicus JCM4427, a GM producer, was explored for novel natural GM derivative(s), resulting in the discovery of new GM analogs as a biosynthetic shunt product and intermediates from its fermentation broth. In this study, the fermentation, isolation, structure determination, and biological activity of the compounds, two new tetracyclic thiazinogeldanamycin (1) and 19-hydroxy-4,5-dihydrogeldanamycin (3), together with the three known 4,5-dihydrothiazinogeldanamycin (2), reblastatin (4), and 17-demethoxy-reblastatin (5), are described.