• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1351-1354
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• 2004

Tetracyclic 5-azaindole analogues were prepared by palladium-catalyzed sequential annulation of benzylidene(3-iodopyridinyl-4-yl)amine and 1-aryl substituted internal alkynes under $Pd(OAc)_2,\;n-Bu_4NCl,\;and Et_3N\;at\;120^{\circ}C.$ The synthetic procedure showed possible diversification of tetracyclic 5-azaindole analogues by varying the 1-aryl substituent in internal alkynes.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.925-932
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• 1992

Total synthesis of 9,10-dideoxyrhodomycinone(30) which is the late-stage precursor of naturally occuring ${\beta}$-rhodomycinone(1) is described. After phthalide sulfone 4 was converted to naphthalide sulfone 12 by the several step. Michale addition of naphthalide sulfone 12 which was converted to an anion with 5-ethyl-1,3-cyclohexenone(21) gave a good yield of linearly condensed tetracyclic ketone compound 26. The keto group of 26 was reduced with sodium borohydride and protected by methyl group to afford compound 28. 9,10-Dideoxy-${\beta}$-rhodomycinone(30) was synthesized from pentamethoxy tetracyclic compound 28 by oxidative demethylation and demethylation of 29.

• Journal of the Korean Chemical Society
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• v.58 no.4
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• pp.423-427
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• 2014

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1623-1628
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• 2002

Tetracyclic pyrido[2,3-b]azepine derivatives 4a-d and 4f as analogues of mirtazapine were synthesized via N-acyliminium ion cyclization by using aromatic rings such as benzene and thiophene ring as a ${\pi}-nucleophile$, and evaluated for the binding affinity for ${\alpha}2-adrenoceptor$. Among tested compounds, 2,3,9,13b-tetrahydro-1H-benzo[f]pyrrolo[2,1-a]pyrido[2,3-c]azepine (4a) was the most potent (Ki = 0.26 ${\mu}M)$ but showed about 3-fold less binding affinity than mirtazapine (Ki = 0.08 ${\mu}M)$ for a2-adrenoceptor.

• Natural Product Sciences
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• v.23 no.2
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• pp.113-118
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• 2017

A new tetracyclic triterpenoid [4,4,24-trimethylcholesta-${\Delta}^{8,9;14,5;24,28}$-trien-$3{\beta},11{\beta},12{\alpha}$-triol-12-acetate, 3-sulfate] sodium salt (1), together with eight known compounds including ergosterol $5{\alpha},8{\alpha}$-endoperoxide (2), 1,9-dihydroxy-3-methoxy-2-methylpterocarpan (3), 3-O-${\beta}$-D-2-acetyl-amino-2-deoxyglucopyranoxyloleanoic acid (4), hydnocarpin (5), derrone (6), isovitexin (7), erythrinin C (8), and 5,4'-dihydroxy-2"-hydroxyisopropyldihydrofurano [4,5:7,8]-isoflavone (9), were isolated from the EtOAc soluble fraction of the methanol extract of aerial part of Desmodium uncinatum collected in the western highland of Cameroon. The structures of these compounds were established by comprehensive interpretation of their spectral data mainly including 1D- ($^1H$ and $^{13}C$), 2D-NMR($^1H$-$^1H$ COSY, HMQC, HMBC) spectroscopic and ESI-TOF-MS mass spectrometric analysis. The isolation of an integracide-like compound from plant origin is a very unusual finding.

• Korean Journal of Pharmacognosy
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• v.1 no.2
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• pp.1-10
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• 1970

The cyclization of geranylgeranyl pyrophosphate followed by ionization, proton elimination or cation center migration produces dicyclic, tricyclic and tetracyclic diterpenoids. The role of some of diterpenoids in animals is well known but their precise functions in plants remain to be explained.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.354-362
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• 2003

A strategy for synthesis of the furan-fused tetracyclic system of xestoquinone was explored through a model study. Using 3-butyn-1-ol as a starting material, 5-iodo-1-methoxymethoxy pentyne (5) was prepared in 5 steps. Reaction of ethyl 2-phenylpropanoate with 5 gave ethyl 7-methoxymethoxy-2-methyl-2-phenyl-5-heptynoate (6) in 88% yield, and then methyl 9-oxo-4-methyl-4-phenyl-2,7-nonadiynoate (13), the key intermediate, was synthesized in 6 steps from the ester 6. Intramolecular cycloaddition reaction of 13 afforded isobenzofuran 14 in 5% yield, which was converted to the tetracyclic structure 15 in the presence of Lewis acid.

• Natural Product Sciences
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• v.14 no.3
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• pp.152-155
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• 2008

An HPLC-ESI-MS method has been developed to identify and quantify two main tetracyclic triterpenes, alisol B 23-acetate and alisol C 23-acetate in the Alismatis Rhizoma (Taeg-Sa). The relative distribution of the two triterpenes in the methanolic extract of commercially available Alismatis Rhizoma was established by selective ion monitoring (SIM) mode via electrospray ionization (ESI) source. Regression equations revealed good linear relationship, and the correlation coefficients were 0.999 and 0.998 for alisol B 23-acetate and alisol C 23-acetate, respectively, between the peak areas of the components and their concentration in a range of $0.06-2.0{\mu}g/mL$. It was found that there were significant differences in the amount of alisol B 23-acetate and alisol C 23-acetate between Korean and Chinese origins. The results showed that this method could be used to identify the two components in Alismatis Rhizoma with high sensitivity and selectivity.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.644-650
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• 1989

Syntheses of phthalide sulfone 2 and naphthalenone 6 followed by new ring annelation methodology of Michael addition using the sulfone anion developed by Hauser-Rhee, furnished linear tetracyclic ring system compound 11. The double bond existing in A-ring of 11 was used to convert to carbomethoxy compound 16, possessing one carbon atom more via Arndt-Eistert synthesis and Wolff rearrangement. Cyclization and hydroxylation of 16 completed the construction of (${\pm}$)-7-Deoxyaklavinone (18).

• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.109-117
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• 1986

7,9-Dideoxydaunomycinone (32), a late-stage precursor of the aglycone of antitumor antibiotic daunorubicin(2a) was prepared from 3-methoxybenzoic acid(5). Thus, 3-methoxybenzoic acid was converted to 4-methoxy-3-(phenylsulfonyl)-1(3H)-isobenzofuranone(11), which furnished trimethoxynaphthoate 16 upon ring annelation developed by Hauser and Rhee. The trimethoxynaphthoate 16 upon ring annelation developed by Hauser and Rbee. The trimethoxynaphtboate 16 was then transformed into phenylsulfonylnaphthofuranone 22, which was used to make anthracenoate 24 via Michael type reaction with 7-(ethylenedioxy)-2-octenoate(23). Conversion of anthracenoate 24 to tetracyclic product 28, followed by subsequent deprotection of the methyl groups in ring-B and C furnished 7, 9-Dideoxydaunomycinone(32).