518-73-0Relevant academic research and scientific papers
Anthraquinone derivatives from Heterophyllaea pustulata
Nunez Montoya, Susana C.,Agnese, Alicia M.,Cabrera, Jose L.
, p. 801 - 803 (2006)
From the leaves of Heterophyllaea pustulata two new monomeric anthraquinones, heterophylline (1,6-dihydroxy-7-methoxy-2-methylanthraquinone, 1) and pustuline (2-hydroxy-3-methoxy-7-methylanthraquinone, 2), and one new bianthraquinone, (S)-5,5′-bisoranjidiol [(S)-5,5′-bis(1,6-dihydroxy- 2-methylanthraquinone), 3], were isolated. Furthermore, the iridoid glycoside asperuloside and three known flavonoids, quercetin, isoquercitrin, and quercetin-3-O-β-D-glucosyl-6″-acetate, were obtained. The structures were determined by analysis of their spectroscopic data and chemical evidence.
Regiospecific Addition of Monooxygenated Dienes to Halo Quinones
Boisvert, Louise,Brassard, Paul
, p. 4052 - 4059 (2007/10/02)
In spite of their decreased polarity with respect to previously studied electron-rich analogues, monooxygenated dienes also react regiospecifically with halo quinones.The corresponding adducts can easily be aromatized on silica gel to isomeric polysubstituted naphthoquinones of unambiguous structure and therefore provide ready access to substrates for subsequent regiospecific annulations.The scope of this approach is illustrated by advantageous syntheses of several natural products: chimaphilin, 6-methylalizarin, 6-methylxantopurpurin, and barleriaquinone.The adductscan also give rise to a series of products in which the oxygen function of the dienes is preserved as a hydroxyl group in the quinone.To this end adducts derived from 1-oxygenated dienes and halo quinones were oxidized effectively with Jones reagent while those obtained from the 2-oxygenated isomers responded better to manganese dioxide.Relative positions of substituens in the adducts were readily confirmed by comparison of some of the hydroxylated oxidation products with known compounds of unambiguous structure.The method is again illustrated by the ready synthesis of a number of natural products including plumbagin, soranjidiol, isochrysophanol and its 8-methyl ether, and isozyganein and its 5-methyl ether.
Regiospecific Reactions of Some Vinylogous Ketene Acetals with Haloquinones and Their Regioselective Formation by Dienolization
Brisson, Clement,Brassard, Paul
, p. 1810 - 1814 (2007/10/02)
Regiospecific reactions of simple 1,3-bis(trimethylsiloxy)-1,3-butadienes with 2,5- and 2,6-dichlorobenzoquinones gave chloronaphthoquinones which, by applying the appropriate vinylketene acetal, provided various monomethyl ethers of isomeric polyhydroxyanthraquinones.The first total synthesis of macrosporin (27) was obtained in this way and the proposed structure for "cajaquinone" (28) found to be incorrect.Simple syntheses of 2-hydroxy-3-methylanthraquinone (16), phomarin (19), soranjidiol (22) and other naturally occuring quinones are also described.The dienolization of 1-methoxy-2,4-pentanedione in the presence of chlorotrimethylsilane gave either 1- or 5-methoxy-2,4-bis(trimethylsiloxy)-1,3-pentadiene, depending upon the reaction conditions.Both dienes react with haloquinones, giving regiospecific products, e.g., tetra-O-methylerythrolaccin (35).
