- Acetylated anthraquinone glycosides from Cassia obtusifolia
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Three new acetylated anthraquinone glycosides (1-3) were isolated from the seed of Cassia obtusifolia, together with one parent anthraquinone glycoside (1a). Their structures were determined on the basis of spectroscopic methods and physicochemical properties as obtusifoline-2-O-β-d-2, 6-di-O- acetylglucopyranoside (1), obtusifoline-2-O-β-d-glucopyranoside (1a), obtusifoline-2-O-β-d-3, 6-di-O-acetylglucopyranoside (2), and obtusifoline-2-O-β-d-4, 6-di-O-acetylglucopyranoside (3).
- Wu, Xiao-Hui,Cai, Jin-Jin,Ruan, Jin-Lan,Lou, Jian-Shi,Duan, Hong-Quan,Zhang, Jun,Cheng, Chun-Ru,Guo, De-An,Wu, Zhi-Yuan,Zhang, Yan-Wen
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- Transition Metal-Catalyzed Oxidations, 6. Total Synthesis of Hallachrome and Related 1,2-Anthraquinones
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9,10-Anthraquinones 3b-3k are prepared by Diels-Alder reaction of juglone (5a) and 7-methyljuglone (5b) with the dienes 4a and 4b, then reduced to the corresponding 1-anthracenols 2b-2d, 2f and 2i that are immediately oxygenated to the ortho-anthraquinones 1b-1d, 1f and 1i with *py*HMPT.The 1,2-anthraquinones dimerize in solution or upon BBr3 treatment.The naturally occurring 1,2-anthraquinone hallachrome (1a) is prepared by selective protection of the bisphenol 3h as monosilyl ether 3i, oxygenation to the silylated ortho-anthraquinone 1i and fluoride-mediated deprotection to 1a. Key words: Hallachrome; 1,2-anthraquinones; 9,10-anthraquinones; oxygenation; 1-anthracenols; Mimoun complex.
- Krohn, Carsten,Khanbabaee, Karamali
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p. 905 - 910
(2007/10/02)
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- DICHLORO QUINONES AS DIENOPHILES; SYNTHESIS OF ALIZARIN DERIVATIVES
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2,3-Dichloro quinonoid dienophiles react with 1,3-dioxy butadienes to give cycloadducts, which aromatise with uptake of external nucleophile to give 1,2-disubstitution in the newly formed aromatic ring.With oxy nucleophiles this has led to synthesis of natural alizarin derivatives.
- Camerom, Donald W.,Feutrill, Geoffrey I.,Keep, Philip L. C.
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p. 5173 - 5176
(2007/10/02)
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- SYNTHESIS OF SPECIFICALLY O-ALKYLATED ANTHRAQUINONES BY CYCLOADDITION
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Cycloadducts from naphthoquinonoid dienophiles and 1-methoxy-1-trimethylsilyloxy butadienes undergo controlled aromatisation to form chiefly α-hydroxy- or α-methoxy-anthraquinones; this has led to synthesis of several natural O-methyl polyoxyanthraquinones.
- Cameron, Donald W.,Feutrill, Geoffrey I.,Gamble, Glenn B.,Stavrakis, John
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p. 4999 - 5002
(2007/10/02)
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