- Catalytic Undirected Intermolecular C-H Functionalization of Arenes with 3-Diazofuran-2,4-dione: Synthesis of 3-Aryl Tetronic Acids, Vulpinic Acid, Pinastric Acid, and Methyl Isoxerocomate
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A variety of 3-aryl tetronic acids have been synthesized by an undirected, intermolecular C-H functionalization of arenes with 3-diazofuran-2,4-dione. This methodology featured as a key step in the synthesis of a series of naturally occurring 3-aryl-5-arylidene tetronic acids (pulvinates) from commercially available tetronic acid. Salient features of the pulvinic acid synthesis include a one-step, stereoselective synthesis of the C5 arylidene group and a single step introduction of the C3 aryl substituent.
- Manchoju, Amarender,Pansare, Sunil V.
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p. 5952 - 5955
(2016/11/29)
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- Chemical constituents of the lichen, Candelaria concolor: A complete NMR and chemical degradative investigation
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A detailed chemical and spectroscopic investigation of the terrestrial lichen Candelaria concolor has yielded several lichenic metabolites belonging to the pulvinic acid series, as well as several depside derivatives including pulvinic dilactone (1), vulpinic acid (4) and calycin (5). The chemical transformation of 1 to pulvinic acid (3) is reported for the first time, as is the conversion of atranorin (6) to 5-chloroatranorin (7) and then finally to 5,5'-dichloroatranorin (8) under very mild conditions. Also presented is the complete 1D and 2D NMR assignment for compounds 1, 3, 4, 5 and 8, including partial NMR chemical shift assignments for the unstable depside (7). Previously, these metabolites had only been partially assigned by NMR spectroscopy.
- Dias, Daniel A.,Urban, Sylvia
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scheme or table
p. 925 - 939
(2010/08/19)
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- Synthesis of vulpinic and pulvinic acids from tetronic acid
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A common precursor, tetronic acid, was used in the synthesis of several vulpinic acids and pulvinic acids, which are pigments found in several lichens and mushrooms. The key features of this method are a two-step alkylidenation of benzyl tetronate and a Suzuki-Miyaura cross-coupling. The synthesis of several natural products, vulpinic acid, pinastric acid, xerocomic acid is described.
- Bourdreux, Yann,Bodio, Ewen,Willis, Catherine,Billaud, Célia,Le Gall, Thierry,Mioskowski, Charles
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p. 8930 - 8937
(2008/12/22)
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- Flexible synthesis of vulpinic acids from tetronic acid
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Several vulpinic acids were synthesized in a few steps from a single precursor, the tetronic acid. This commercial compound was converted in a few steps to an iodide. Suzuki-Miyaura cross-couplings involving this common intermediate and various arylboronates allowed to gain access to several vulpinic acids (or methyl pulvinates). Among them, two natural products, vulpinic acid and pinastric acid, were prepared.
- Willis, Catherine,Bodio, Ewen,Bourdreux, Yann,Billaud, Célia,Gall, Thierry Le,Mioskowski, Charles
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p. 6421 - 6424
(2008/02/12)
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- Uncatalyzed reaction of silyl ketene acetals with oxalyl chloride: A straightforward preparation of symmetrical pulvinic acids
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(Chemical Equation Presented) Several natural pulvinic acids were synthesized. Silyl ketene acetals derived from methyl arylacetates (4 equiv) reacted with oxalyl chloride at -78°C, without the need of adding a catalyst. After treatment of the crude diketones with DBU and acidification with hydrochloric acid, symmetrical pulvinic acids methyl esters were obtained. Saponification of the methyl esters afforded the corresponding pulvinic acids in 60-70% overall yields from oxalyl chloride.
- Heurtaux, Benoit,Lion, Claude,Le Gall, Thierry,Mioskowski, Charles
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p. 1474 - 1477
(2007/10/03)
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- Suzuki cross-coupling reactions of γ-alkylidenebutenolides: Application to the synthesis of vulpinic acid
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α-Hydroxy-γ-alkylidenebutenolides were efficiently functionalized by Suzuki cross-coupling reactions via the corresponding enol triflates. The natural product vulpinic acid was prepared by this methodology.
- Ahmed, Zafar,Langer, Peter
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p. 3753 - 3757
(2007/10/03)
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- Synthesis of Grevillins, Novel Pyrandione Pigments of Fungi. Biogenetic Interrelationships between Grevillins, Pulvinic Acids, Terphenylquinones and Xylerythrins
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A synthesis of the grevillin group of pyrandione pigments, e.g. 3, 23 and 24 present in fungi is described.The synthesis, which is based on a biogenetic model, uses bis-benzylacyloins 9 and their corresponding oxalate derivatives as key intermediates (Scheme 3).Treatment of the grevillins 25a-c with sodium ethoxide in ethanol effects their quantitative isomerisation into the corresponding terphenylquinone pigments 4a-c.Perkin-type condensations between the terphenylquinones 4 and arylacetic acids in the presence of sodium acetate-acetic anhydride then produces the xylerythrin pigments 29a-e, whereas rearrangements of 4 in the presence of dimethyl sulphoxide leads to pulvinic acid derivative, e.g. 31, 32 and 5.These synthetic studies interrelate the biosynthetic origins of the pigment types 3, 4, 5 and 8 together with the related pulvinones 6 and furanone 7 fungal pigments.
- Pattenden, Gerald,Pegg, Neil A.,Kenyon, Ronald W.
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p. 2363 - 2372
(2007/10/02)
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- Dioxolanones as Synthetic Intermediates. Part 3. Biomimetic Synthesis of Pulvinic Acids
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The reaction of the phosphorane (16) with methyl arylglyoxylates gives 5-(α-methoxycarbonylarylidene)-2,2-pentamethylene-1,3-dioxolan-4-ones which have been treated with the lithium enolates of t-butyl phenylacetic esters to provide a biomimetic synthesis of pulvinic acids.By this method pulvinic acid (2), vulpinic acid (1), and the unsymmetrically substituted compounds, leprapinic acid (3), and xerocomic acid (4) have been prepared; the last named was obtained via an intermediate (28) in which the phenolic groups were protected as benzyl ethers.
- Ramage, Robert,Griffiths, Gareth J.,Sweeney, John N. A.
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p. 1547 - 1553
(2007/10/02)
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