• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.116-116
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• 2003

In 1998, Osada and co-workers isolated 140 mg of a novel cytokine modulator from 18 L of the culture broth of Streptomyces RK95- 31 isolated from a soil sample in Hiroshima Prefecture. This new immunosuppressant was named (-)-cytoxazone and its absolute configuration was determined on the basis of its NMR, CD and X -ray analysis. It interferes with cytokine IL4, IL10 and IgG production by selective inhibition of the signaling pathway of Th2 cells, but not Thl cells. Inhibitors of Th2-dependent cytokine production have potential as potent chemotherapeutic agents in the field of immunotherapy. The (-)-cytoxazone is different from known immunomodulators such as FK 506 and rapamycin in respect of structure and biological activity. As such cytoxazone should be a useful tool for understanding signaling pathways in Th2 cells, the synthesis of (-)-cytoxazone is of interest for the development of new cytokine modulators.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1003-1008
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• 2009

The $O_sO_4$-catalyzed dihydroxylations of a monosubstituted allylic amine and $\gamma-amino-\alpha,\;\beta-unsaturated$ (E)-esters with bulky alkyl groups showed a high anti-selectivity. Since the acyclic conformation of N-acyloxy protected allylic amines was efficiently controlled by a bulky t-Bu or OBO ester group, the anti diastereoselectivity of >12.5:1 was obtained without applying a chiral reagent. The synthetic utility of the present method was demonstrated by a stereoselective and efficient synthesis of an $\alpha$-glucosidase inhibitor 15 from commercially available N-Cbz-L-serine 6 in 11 steps and 31% yield.

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.623-626
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• 2003

Nematophin and its analog incorporating tryptamine unit have been isolated and characterized from strain XRPC of a symbiotic bacterium Xenorhabdus nematophilus, which was newly isolated from Korean entomopathogenic nematodes. The stereoselective synthesis of these compounds was accomplished, and the relative configurations were determined. Nematophin exhibited potent antibacterial activities over several strains of methicillin-resistant S. aureus (MRSA) comparable to those of vancomycin.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.235-237
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• 1987

(7Z, 11E)-7, 11-Hexadecadien-1-yl acetate(1), the sex pheromone of the female Angoumois grain moth, Sitotroga cerealella, was synthesized via the acetylenic intermediate, (11E)-11-hexadecen-7-yn-ol THP ether(2). The acetylenic compound was prepared from 7-octyn-1-ol THP ether(4) and (3E)-1-bromo-3-octene(3). The (E)-homoallylic bromide 3 was synthesized by the Julia olefin synthesis of 1-cyclopropylpentan-1-ol(6).

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.182.3-183
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• 2003

(-)-Antofine is phenanthroindolizidine alkaloid being isolated from Cynanchum vincetoxicum. It has powerful cytotoxicity toward drug-sensitive KB-3-1 and multidrug resistant KB-V1 cancer cell line. We have successfully accomplished stereoselective total synthesis by using palladium catalyzed Stille coupling of l0-bromomethyl-2,3 ,6-trimethoxy-phenanthrene and (R)-(E)-4-(tributylstannanyl)but-3-en-2-o1, Overmann rearrangement of imidate, and RCM(ring-closing metathesis) for construction of pyrrolidine.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.346-351
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• 2007

Efficient stereoselective synthesis of α,β-Unsaturated acids, α-Cyanoacrylonitriles and α-Cyanoacrylates has been carried out in the presence of NaHSO4·SiO2 under solvent?free conditions with an E-geometry.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2139-2152
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• 2007

Ruthenium complex-catalyzed reactions often require highly qualified tuning of reaction conditions with substrates to attain high yield and selectivity of the products. In this review, our strategies for achieving characteristic ruthenium complex-catalyzed co-oligomerization of different alkenes are disclosed: 1) The codimerization of 2-norbornenes with acrylic compounds by new ruthenium catalyst systems of RuCl3(tpy)/Zn [tpy = 2,2':6',2''-terpyridine] or [RuCl2(η6-C6H6)]2/Zn in alcohols, 2) A novel synthesis of 2-alkylidenetetrahydrofurans from dihydrofurans and acrylates by zerovalent ruthenium catalysts, such as Ru(η4-cod)(η6-cot) [cod = 1,5-cyclooctadiene, cot = 1,3,5-cyclooctatriene] and Ru(η6-cot)(η2-dmfm)2 [dmfm = dimethyl fumarate], 3) Regio- and stereoselective synthesis of enamides by Ru(η6-cot)(η2-dmfm)2-catalyzed codimerization of N-vinylamides with alkenes, and 4) Unusual head-to-head dimerization of styrenes and linear codimerization of styrenes with ethylene by Ru(η6-cot)(η2-dmfm)2 catalyst in the presence of primary alcohols.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.588-592
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• 1992

A series of new ferrocene derivatives containing cyclohexylphosphines have been prepared from the reactions of lithioferrocenes with corresponding chlorodicyclohexylphosphines. 1-diphenylphosphino-1'-dicyclohexylphosphinoferro cene has been prepared from [1]-ferrocenophane via a ring cleavage reaction. Chiral ferrocenylaminophosphines incorporating cyclohexyl-and cyclopentadienylphosphines have also been prepared from the chiral template 2-N,N-dimethylaminoethylferrocene (FA) via stereoselective lithiation followed by phosphination with corresponding $R_2PCl$(R= $C_6H_{11}$, $C_5H_5$). The synthesis of cyclopentadienylphosphine derivative of (R)-FA (6b) led to the formation of a mixture of four diastereomers due to the presence of three chiral sources in the final product in addition to the fluxional behavior of the $η^1$-$C_5H_5$ group attached to the phosphorus. All these new compounds have been characterized by analytical and spectroscopic techniques.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1662-1668
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• 2011

Steric and electronic parameters of 4'-substituents play significant roles in steering the conformation of nucleoside analogues. In order to investigate the relationship of 4'-substituent with antiviral enhancement, novel 4'-phenyl-5'-norcarbocyclic adenosine phosphonic acid analogues were racemically synthesized via de novo acyclic stereoselective route from propionaldehyde 5. The phenyl substituted cyclopentenols 15a and 15b as key intermediates were successfully constructed via reiterative carbonyl addition of Grignard reagents and ring-closing metathesis of corresponding divinyl 14. The synthesized nucleoside phosphonic acids analogues 19, 20, 21, and 23 were subjected to antiviral screening against HIV-1.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2039-2042
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• 2009

As a part of an ongoing effort to discover inhibitors of the Hepatitis C Virus RNA replication, we describe here the first synthetic route of 1'($\alpha$),2'($\beta$)-C-dimethyl carbocyclic adenine analogue. The key intermediate cyclopentenyl alcohol 8($\alpha$) was prepared from aldehyde 4 using ring-closing metathesis (RCM) as a key reaction. Coupling of 8($\alpha$) with nucleosidic base via the regioselective Mitsunobu reaction followed by stereoselective dihydoxylation and deprotection afforded the target carbocyclic adenine analogue 12.