• Archives of Pharmacal Research
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• 제27권10호
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• pp.1029-1033
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• 2004

From the methanol extract of the whole plants of Carpesium macrocephalum $F_R$. et $S_{AV}$., five sesquiterpene lactones (1: carabron, 2: tomentosin, 3: ivalin, 4: 4H-tomentosin, 5: carabrol) and three terpenoids (6: loliolide, 7: vomifoliol, 8: citrusin C) were isolated. The structures and stereochemistry of compounds 1-8 were established on the basis of chemical analysis as well as 1D- and 2D-NMR spectroscopy. Among them, compounds 2, 4, and 6-8 were isolated for the first time from Carpesium species.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2608-2612
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• 2009

The unequivocal solid-state structure and stereochemistry of the hetaryl leuco-TAM dye, 2,2’-(2-phenyl propane- 1,3-diylidene) bis(1,3,3- trimethylindoline) derivatives were established using X-ray single crystal analysis. The X-ray crystal analysis showed that the (Z, E)-isomers only formed stereoselectively, with a so-called “threebladed propeller” conformation, from the reaction of a Fischer base and benzaldehyde derivatives. These isomers were stacked in a juxtaposition to form a dimer or a double dimer, adopting either a triclinic, with P-1, or monoclinic crystal system with a space group P21/n in the unit cell of the crystal.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.990-994
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• 2007

Bioassay-guided fractionation of the MeOH extract from the sponge Discodermia calyx collected off the coast of Jeju Island, South Korea, led to the isolation of a polyketide, icadamide C (1), along with previously reported theopederin K (3). Structure elucidation was performed by a combination of high resolution mass and 2D-NMR (principally COSY, HMBC, HSQC, and NOESY) spectroscopy. Stereochemistry of compound 1 was determined as 2R*, 3R*, 6R*, 10S*, 11S*, 12R*, 13S*, 15R* and 2'S by NMR data and Marfey analysis. Isolated metabolites displayed potent cytotoxic activity against a small panel of five human solid tumor cell lines with ED50 values of less than 0.1 μg/mL.

• Archives of Pharmacal Research
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• 제24권4호
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• pp.300-306
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• 2001

A novel and two known bioactive mono-tetrahydrofuran (THF) annonaceous acetogenins, annomocherin (1), annonacin (2) and annomontacin (3), have been isolated from the fractionated ethanolic extracts of the seeds of Annona cherimolia, guided by the brine shrimp lethality test (BST). Their structures were elucidated on the basis of spectroscopic and chemical methods. All compounds have a relative stereochemistry of threo/trans/threo for the mono-THF ring with two flanking hydroxyls. Compound 1 has a double bond at C-23/ 24 of aliphatic chain. Compound 1 was isolated from natural sources for the first time, and was named annomocherin. Two known Compounds 2 and 3 which have never been isolated from this species before, were obtained. Compound 1 exhibited potent and selective cytotoxicities against the breast carcinoma (MCF-7) and kidney carcinoma (A-498) cell lines with 100 to 1,000 times the potency of adriamycin. In brine shrimp lethality test (BST), 1-3 exhibited cytotoxicity.

• Natural Product Sciences
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• 제13권4호
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• pp.355-358
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• 2007

Further bioactivity-directed fractionation of the ethanol extract of the seeds of Annona cherimolia has led to the isolation of two mono-tetrahydrofuran acetogenins, xylomaticin (1) and gonionenin (2). The structures of these compounds were characterized on the basis of chemical and spectroscopic data. Compounds 1 and 2 have a relative stereochemistry relationship of threo/trans/threo across the mono-tetrahydrofuran ring with its two flanking hydroxyls. Compounds 1 and 2 are known, but are first isolated from this plant. In brine shrimp lethality test (BST), 1 and 2 exhibited cytotoxic activity.

• Bulletin of the Korean Chemical Society
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• 제6권3호
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• pp.135-138
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• 1985

A new flexible $N_2O_2$-type tetradentate ligand, ethylene-diamine-N,N'-di-${\alpha}$-butyric acid (eddb), has been synthesized, and a series of cobalt (III) complexes of eddb, $[Co(edda)(L)]^{n+}$ (L = $Cl_2$, $(H_2O)_2$, $Cl\;H_2O$, and $Co^2_3$), have been prepared. Only s-cis isomers have been yielded during the preparation of complexes. Ring strain is cited as the primary cause for the preference for the s-cis geometric configuration.

• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.732-739
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• 1994

Asymmetric [2,3]-Wittig rearrangements of allyl propargyl ethers in hexane were performed in the presence of s-butyllithium and (-)-${\alpha}$-isosparteine which is a $C_2$-symmetric chiral ligand for the alkyllithium reagent. The reactions of (Z)-or (E)-allyl 3-trimethylsilylpropargyl ethers at -78$^{\circ}C$ showed good diastereoselectivities (74-100%) and moderate enantioselectivities (29-71%). The absolute configurations of the rearrangement products were determined by the corresponding Mosher's esters. It was found that (-)-${\alpha}$ -isosparteine induced (R) configuration at the hydroxy carbon and syn stereochemistry more favorably. The possible transition state is discussed.

• Bulletin of the Korean Chemical Society
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• 제17권11호
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• pp.1031-1036
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• 1996

The synthesis and characterization of diastereomeric dodecanucleotides, d[GATCp(S)TCGAGATC], containing recognition sequence of the XhoI restriction endonuclease with a phosphorothioate internucleotidic linkage the cleavage site are described. Rp and Sp form of diastereomerically pure dinucleoside phosphorothioates d[Cp(S)T] were presynthesized and used for the addition to the growing oligonucleotide chain as a block. The stereochemistry of dinucleoside phosphorothioate was assigned by 31P NMR spectroscopy, enzyme digestion, and reverse-phase HPLC. XhoI restriction endonuclease cut only Rp diastereomer d[GATCp(S))TCGAGATC]. The rate of hydrolysis is slower than that of the unmodified dodecamer d[GATCTCGAGATC]. The phosphorothioate nucleotide is using for determination of the stereochemical course of the XhoI catalyzed reaction.

• Bulletin of the Korean Chemical Society
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• 제6권6호
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• pp.369-374
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• 1985

A new flexible quadridentate ligand, N,N'-dimethylethylenediamine-N,N'-di-${\alpha}$-propionic acid (dmedpa) has been synthesized, and diammine and ethylenediamine cobalt(III) complexes of dmedpa, $[Co(dmedpa)(NH_3)_2]^+$ and $[Co(dmedpa(en)]^+,$ have been prepared. Only s-cis isomer has been yielede. A known N,N'-dimethylethylediamine-N,N'-diacetic acid (dmedda) has also been prepared. Dichloro cobalt(III) complexes of both dmedda and dmedpa have been prepared. Only the s-cis isomer has been yielded in the $[Co(dmedda)Cl_2]^-$ complex, while only the uns-cis isomer has been obtained for the $[Co(dmedpa)Cl_2]^-$ complex.

• Bulletin of the Korean Chemical Society
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• 제14권4호
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• pp.487-490
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• 1993

A semiempirical methods (PM3-CI-UHF. etc.) for the evaluation of ground and excited state electronic structures of psoralens are applied to angelicin with thymine. The photocycloaddition reaction of angelicin with thymine were deduced to be formed by their preferable HSOMO-LUMO interactions. The photoadduct was inferred to be a C$_{4-}$cycloaddition product with the stereochemistry of cis-anti formed through [2+2] addition reaction between, the 3,4 double bonds of angelicin and the 5,6-double bond of thymine.