Chemical and Pharmaceutical Bulletin p. 222 - 230 (1998)
Update date:2022-07-29
Topics:
Horie, Tokunaru
Shibata, Kenichi
Yamashita, Kazuyo
Fujii, Kenichi
Tsukayama, Masao
Ohtsuru, Yoshizumi
2',4'-Bis(benzyloxy)-3',6'-dimethoxychalcones (5), which were obtained from the dibenzyl ether of 2,4-dihydroxy-3,6-dimethoxyacetophenone (3), were oxidatively rearranged with thallium (III) nitrate in methanol and the resultant products were converted into 7-hydroxy-5,8-dimethoxyisoflavones (8) by hydrogenolysis, followed by cyclization. The isoflavones were quantitatively demethylated to 5,7-dihydroxy-8-methoxyisoflavones (2) via their acetates. The isomeric 5,7-dihydroxy-6-methoxyisoflavones (1) were also synthesized from the chalcones, obtained from 2,3-dimethoxy- (16) or 2- isopropoxy-3-methoxy-4,6-bis(benzyloxy)acetophenones (21), by a similar method. On the other hand, the isoflavones with two hydroxy groups at the 2'- and 4'-positions were easily synthesized by the following method. Treatment of the rearranged product from 2,2',4,4'-tetrakis(benzyloxy)-3'6'- dimethoxychalcone (5f) with hydrochloric acid (HCl) in acetic acid afforded 2',4',7-tris(benzyloxy)-5,8-dimethoxyisoflavone (10f). The 5-methoxy group in the isoflavone was quantitatively cleaved to give the corresponding 5- hydroxyisoflavone (11f), which was isomerized to 2',4',7-tris(benzyloxy)-5- hydroxy-6-methoxyisoflavone (25f) in the presence of anhydrous potassium carbonate. Hydrogenolysis of the two 5-hydroxyisoflavones proceeded smoothly to give 2',4',5,7-tetrahydroxy-8-(2f) and 6-methoxyisoflavones (1f), respectively. The 13C-NMR spectra of these isoflavones supported the proposed structures of polyhydroxyisoflavones. The proposed structures of two natural isoflavones were revised.
View MoreHuangshan Honghui Pharm Technology Co., Ltd.(expird)
website:http://www.honghuichem.com
Contact:18855958372
Address:Qingshan Wan No.1,Nanyuan Kou,SheXian Huangshan City,Anhui Province
Contact:0510-85393305
Address:1619 Huishan Avenue, Huishan District, Wuxi,
LINYI FUDE FINE CHEMICAL CO.,LTD
Contact:86-539-2361184
Address:YISHUI, LINYI,SAHNDONG,CHINA
Twin International Co., Limited
Contact:+86-21-80309280
Address:No.345 Jinxiang Road, Jinqiao Export Processing Zone
Zhejiang Newfine Industry Co.,Ltd.
Contact:+86-573-82262042
Address:No.225,Dongqing Road, garoms@163.com
Doi:10.1039/P19810003186
(1981)Doi:10.1002/jccs.200300124
(2003)Doi:10.1016/j.mencom.2019.05.018
(2019)Doi:10.1007/BF00673338
()Doi:10.1039/c8cc00980e
(2018)Doi:10.1016/S0014-827X(03)00165-4
(2003)