- A PENTACYCLIC QUINONE AND DIOSINDIGO B FROM THE HEARTWOOD OF DIOSPYROS MELANOXYLON
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Diosindigo A, diosindigo B and biramentaceone have been isolated from heartwood of Diospyros melanoxylon.A violet pigment isolated from the same source has been shown to be a new pentacyclic quinone.Sunlight causes diosindigo B to change to the pentacyclic quinone and biramentaceone.The intense peaks at m/e 389 and 388 in the mass spectrum of diosindigo B are doublets which arise by fragmentation of both M+ and M+ + 2.Key Word Index- Diospyros melanoxylon; Ebenaceae; naphthaquinones; diosindigo B; rearrangement; diosindigo A; biramentaceone.
- Sankaram, Akella V. B.,Reddy, Vaddu V. Narayana,Sidhu, Gurbachan S.
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- Oxidative coupling of methoxynaphthylenediols
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The oxidative coupling of a mixture of 1-methoxy-7-methyl-4,5- naphthylenediol and 4-methoxy-7-methyl-1,5-naphthylenediol using lead(IV) oxide gives the symmetrical bisnaphthalene indigos diosindigo A and diosindigo B together with the corresponding unsymmetrical isomer. Oxidation of the first two by nitric acid gives the binaphthyldiquinones mamegakinone and biramentaceone, respectively; the third gives the unsymmetrical diquinone rotundiquinone. Similar oxidations of related naphthylenediols are described.
- Maiti, Bhim C.,Musgrave, Oliver C.,Skoyles, Douglas
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p. 6568 - 6574
(2007/10/03)
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- Biomimetic synthesis of the dinaphthofuranquinone violet-quinone, utilizing oxidative dimerization with the ZrO2/O2 system
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The first total and biomimetic synthesis of violet-quinone (1), which has a dinaphthofuranquinone (DNFQ) framework, is described. This synthesis features the oxidative dimerization of 1-naphthol 4 and the construction of the DNFQ framework by photochemica
- Ogata, Tokutaro,Okamoto, Iwao,Kotani, Eiichi,Takeya, Tetsuya
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p. 3941 - 3948
(2007/10/03)
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- Ebenaceae Extractives. Part 9. New Naphtoquinones and Binaphthylquinones from Macassar Ebony
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In addition to macassar II (1) and its methyl ether, macassar III, the heartwood of Diospyros celebica contains diomelquinone A (2), the o-naphtoquinone (3), celebaquinone (8), isocelebaquinone A (21), and diosindigo B (10) and its dihydro-derivative (13).These extractives appear to be related biogenetically to the dihydric methoxynaphtols (15) and (27).Two other products, diosindigos B1 (17) and B2 (18), which contain ethoxy groups, are artefacts formed during the extraction procedure.
- Maiti, Bhim C,Musgrave, Oliver C.
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p. 675 - 682
(2007/10/02)
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- Dimeric Naphthoquinones, IV1). - Synthesis of Biramentaceone, Mamegakinone and Rotundiquinone
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Mamegakinone (8a), biramentaceone (12a), 3,3'-bijuglone (8b), 2,2-bijuglone (12b) and their methyl ethers were prepared by oxidative coupling of substituted 4-methoxy-1-naphthols; indigoids like 24 are intermediates.Cooxidation of the isomeric dimethoxy-1
- Laatsch, Hartmut
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p. 1321 - 1347
(2007/10/02)
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