- Preparation method and intermediates of flavonoids
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The invention discloses a preparation method and intermediates of flavonoids. The preparation method comprises the following steps: in a solvent, in the presence of an acid, performing a ring-opening reaction and an elimination reaction on a compound 8 to obtain a compound 9. Raw materials used in the method are easy to acquire, and the method has high yields and simple post processes, and does not need column chromatography.
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Paragraph 0235-0237
(2017/11/16)
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- Preparation method of flavonoids
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The invention discloses a preparation method of flavonoids. The method comprises the following step: in a solvent, in the presence of iodine and a silver salt or in the presence of iodine and a copper salt, performing an iodination reaction on a compound 1 to obtain a compound 2. Raw materials used in the method are easy to acquire, and the method has high yields and simple post processes, and does not need column chromatography.
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Paragraph 0235-0237
(2017/11/16)
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- Facile synthesis of norwogonin, isoscutellarein, and herbacetin
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An expeditious synthesis of norwogonin, isoscutellarein, and herbacetin, has been accomplished by a strategy featuring a borylation of sterically hindered aryl iodide and a one-pot oxidation to generate the C-3 and C-8 OH groups. The total synthesis gives excellent yields and conventional flash column chromatography is not needed for purification.
- Yuan, Hu,Ye, Ji,Chen, Hao,Zhao, Zeng,Luo, Xukai,Zhang, Weidong,Sun, Qingyan
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supporting information
p. 3389 - 3391
(2016/07/11)
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- Synthetic Studies of the Flavone Derivatives. VIII. Synthesis of Kanzakiflavones and Their Isomers
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Kanzakiflavone-1 and -2, isolates from Iris Unguicularis, and their position isomers were synthesized to confirm the structures of the isolates.The differences among these flavones are discussed on the basis of spectral data.Keywords: kanzakiflavone-1; kanzakiflavone-2; 4',5-dihydroxy-7,8-methylenedioxyflavone; 6,7-methylenedioxy-4',5,8-trimethoxyflavone; 7,8-methylenedioxy-4',5,6-trimethoxyflavone; 3'-acetyl-4',5-dihydroxy-6,7-methylenedioxyflavone
- Iinuma, Munekazu,Tanaka, Toshiyuki,Matsuura, Shin
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p. 1006 - 1010
(2007/10/02)
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- Studies of the Selective O-Alkylation and Dealkylation of Flavonoids. VI. Demethylation of 8-Hydroxy-5,7-dimethoxyflavones with Anhydrous Aluminum Chloride or Bromide in Acetonitrile
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The demethylation of seven 8-hydroxy-5,7-dimethoxyflavones with anhydrous aluminum chloride or bromide in acetonitrile was studied and the following results were obtained. (1) Anhydrous aluminum chloride in acetonitrile selectively split the 5-methoxyl group without cleavage of the 7-methoxyl group, and seven 5,8-dihydroxy-7-methoxy-flavones were quantitatively synthesized by the demethylation. (2) In the demethylation with anhydrous aluminum bromide, the 5- and 7-methoxyl groups on 4',5,7-trimethoxy- and 3',4',5,7-tetramethoxy-8-hydroxyflavone were selectively split to give the corresponding 5,7,8-trihydroxyflavones in good yield.However, the demethylation was not accessible to the synthesis of 5,7,8-trihydroxy-3',4',5'-trimethoxyflavone, 4',5,7,8-tetrahydroxy-3'-methoxy-, and 3',5,7,8-tetrahydroxy-4'-methoxyflavone, because of the cleavage of the methoxyl groups on the B ring.The synthesized flavones were employed for the identification of the two natural flavones, which were proposed to be 4',5,8-trihydroxy-7-methoxyflavone and 4',5,8-trihydroxy-3',7-dimethoxyflavone.The former, salvitin, was revised to 4',5,7-trihydroxy-6-methoxyflavone and the latter seemed to be 4',5,7-trihydroxy-3',8-dimethoxyflavone.
- Horie, Tokunaru,Kourai, Hiroki,Fujita, Nobuhisa
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p. 3773 - 3780
(2007/10/02)
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