Four New 6-Nor-5(6→7)<i>abeo</i>-abietane Type Diterpenes and Antitumoral Cytotoxic Diterpene Constituents from the Bark of<i>Taiwania cryptomerioides</i>

Chang, Chi I.; Chang, Jang Yang; Kuo, Ching Chuan; Pan, Wen; Kuo, Yueh Hsiung

doi:10.1055/s-2005-837754

Cited by 81 publications

(79 citation statements)

References 19 publications

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“…The taiwaniaquinoids are a family of unusual diterpenoids possessing a [6,5,6]- abeo -abietane skeleton that was unknown in nature prior to 1995 1–7. Each member of this family contains a benzylic quaternary stereogenic center (Figure 1).…”

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confidence: 99%

Enantioselective Total Syntheses of (−)-Taiwaniaquinone H and (−)-Taiwaniaquinol B by Iridium-Catalyzed Borylation and Palladium-Catalyzed Asymmetric α-Arylation

2011

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We report a concise, enantioselective total synthesis of (−)-taiwaniaquinone H and the first enantioselective total synthesis of (−)-taiwaniaquinol B by a route that includes enantioselective, palladium-catalyzed α-arylation of a ketone with an aryl bromide that was generated by sterically controlled halogenation via iridium-catalyzed C-H borylation. This asymmetric α-arylation creates the benzylic, quaternary stereogenic center present in the taiwaniaquinoids. The synthesis was completed efficiently by developing a Lewis acid-promoted cascade to construct the [6,5,6] tricyclic core of an intermediate common to the synthesis of a number of taiwaniaquinoids. Through the preparation of these compounds, we demonstrate the utility of constructing benzylic, quaternary, stereogenic centers, even those lacking a carbonyl group in the α-position, by asymmetric α-arylation.The taiwaniaquinoids are a family of unusual diterpenoids possessing a [6,5,6]-abeoabietane skeleton that was unknown in nature prior to 1995. 1-7 Each member of this family contains a benzylic quaternary stereogenic center (Figure 1). Studies of the biological activities of taiwaniaquinoids are ongoing, but preliminary data have indicated that some members of this family exhibit antitumor activities. [8][9][10][11] The structural features and the biological activities of these compounds have led many groups to report total and formal syntheses of the taiwaniaquinoids. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] However, the majority of these syntheses have targeted racemic versions of this class of natural products.Asymmetric syntheses of the taiwaniaquinoids are challenging due to the limited number of enantioselective reactions that establish quaternary stereogenic centers.26 -29 One approach that eliminates this challenge is to prepare the material by a ring-contractive derivatization of enantioenriched terpenes. Alvarez-Manzaneda and co-workers prepared (−)-taiwaniaquinone G (1), 22 (−)-taiwaniaquinone H (2) and (−)-dichroanone (3) in 15 or 16 steps from (+)-sclareolide, 23 and Gademann and coworkers prepared (−)-taiwaniaquinone H (2) in 13 steps from methyl dehydroabiate. 25 Recently, Alvarez-Manzaneda and co-workers reported the syntheses of (−)-taiwaniaquinone A (4) in 15 steps and (−)-taiwaniaquinone F (5) in 16 steps from (+)-podocarpa-8(14)-en-13-one. 30 To date, only two enantioselective total syntheses of taiwaniaquinoids from achiral or racemic starting materials have been reported. McFadden and Stoltz reported an 11-step synthesis of (+)-dichroanone (ent-3) in which the quaternary stereogenic center was set by an asymmetric Tsuji allylation. 17 jhartwig@illinois.edu. Supporting Information Available: Experimental details, characterization data, and 1 H and 13 C NMR spectra. This material is available free of charge via the Internet at http://pubs.acs.org. Recently, Node and coworkers employed an enantioselective, intramolecular Heck reaction for the total syntheses of (−)-dichroanal B (6) in 12 steps, (−)-dichroa...

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confidence: 99%

Enantioselective Total Syntheses of (−)-Taiwaniaquinone H and (−)-Taiwaniaquinol B by Iridium-Catalyzed Borylation and Palladium-Catalyzed Asymmetric α-Arylation

2011

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“…18) In these woods, a variety of biologically active abietane-type and two pimarane-type diterpenoids have been isolated. [22][23][24][25][26][27][28][29][30][31] These reports are indicative that yellow hornets utilize these woods not only for building material for the nest but also as a chemical tool to protect the nest from microorganisms.…”

Section: Discussionmentioning

confidence: 99%

“…[22][23][24][25][26][27][28][29][30][31] However, these molecular mechanisms have not been well examined. Ross reported that an anticancer quinone classified as an abietane terpenoid exhibited apoptosis, based on morphological changes in the cancer cells.…”

Section: Discussionmentioning

confidence: 99%

A Quinone Isolated from the Nest of Vespa simillima and Its Growth-Inhibitory Effect on Rat Liver Cancer Cells

Fujiwara

Mangetsu

Yang

et al. 2008

Biological & Pharmaceutical Bulletin

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A biologically active quinone that exhibits a growth-inhibitory effect on rat liver cancer cells was isolated from the nest of a social wasp, Vespa simillima (Vespinae, Vespidae). The structure was unambiguously determined by NMR and synthetic experiments and identified as being 7,8-seco-para-ferruginone. The synthetic quinone showed potent growth-inhibitory effects on rat hepatoma cells (IC 50 value‫9.1؍‬ m mM). Morphological analyses of dRLh84 cells using the synthetic compound were tested. Chromatin coagulation was induced by the synthetic compound at 31.6 m mM.

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“…Our particular attention was taken by the norditerpene taiwaniaquinone G (6). [5] This molecule has not only undergone biosynthetic excision of a carbon atom, but it also lacks the unsaturation and/or oxygen functionality that would be immediately amenable to biomimetic chemistry. Taiwaniaquinone G (6) has been the target of two previous syntheses (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Cationic Polyene Cyclization for Taiwaniaquinoid Construction

2017

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Four New 6-Nor-5(6→7)abeo-abietane Type Diterpenes and Antitumoral Cytotoxic Diterpene Constituents from the Bark ofTaiwania cryptomerioides

Cited by 81 publications

References 19 publications

Enantioselective Total Syntheses of (−)-Taiwaniaquinone H and (−)-Taiwaniaquinol B by Iridium-Catalyzed Borylation and Palladium-Catalyzed Asymmetric α-Arylation

Enantioselective Total Syntheses of (−)-Taiwaniaquinone H and (−)-Taiwaniaquinol B by Iridium-Catalyzed Borylation and Palladium-Catalyzed Asymmetric α-Arylation

A Quinone Isolated from the Nest of Vespa simillima and Its Growth-Inhibitory Effect on Rat Liver Cancer Cells

Cationic Polyene Cyclization for Taiwaniaquinoid Construction

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