Bulletin of the Chemical Society of Japan p. 2033 - 2041 (1995)
Update date:2022-08-04
Topics:
Horie
Kobayashi
Kawamura
Yoshida
Tominaga
Yamashita
In the demethylation of 6-hydroxy-3,4',7-trimethoxy-5-(tosyloxy)flavone with anhydrous aluminum bromide, the 5-tosyloxyl group was eliminated with bromination to give 8-bromo-3,6,7-trihydroxy-4'-methoxyflavone as the main product. When anhydrous aluminum chloride was used in the demethylation of the acetate, the 5-tosyloxyl group was cleaved prior to the demethylation to give 5,6,7-trihydroxy-3,4'-dimethoxyflavone. Demethylation of 6-hydroxy-4',5,7-trimethoxy-3-(tosyloxy)flavone and its acetate with the bromide or chloride afforded the 5,6,7-trihydroxyflavone without the cleavage of the 3-tosyloxyl group, but was not suitable for the general synthesis of the 3,5,6,7-tetrahydroxyflavones because of the difficulty in removing the protecting group. Consequently, it was found that the direct demethylation of 3,6-dihydroxy-5,7-dimethoxyflavones with anhydrous aluminum chloride-sodium iodide in acetonitrile was the most useful general method for synthesizing 3,5,6,7-tetrahydroxyflavones. Additionally, the reported structures of two natural flavones were revised.
View MorePuyang Huicheng Electronic Material Co., Ltd
website:http://huichengchem.weba.testwebsite.cn/index_en.html
Contact:+86-393-8910800
Address:West Section Shengli Road, Puyang457000, China
website:http://www.china-sinoway.com
Contact:+86-592-5853819
Address:16/F,Huicheng Comm,Complex,No839 XiaHe Rd, Xiamen,China
Contact:+86-27-85733560
Address:NO.308,QINGNIAN RD.,WUHAN,CHINA
Jintan Jinnuo Chemical Co., Ltd.
Contact:+86-519-80199901
Address:Room 1804, Building 1, Huacheng Business Plaza, Jintan, Jiangsu, China
Contact:0086-22-2822 1962 / 2822 1963
Address:B-808, No. 1, North-South Street, Hexi District,
Doi:10.1002/anie.201610888
(2017)Doi:10.1016/S0040-4020(01)91343-2
(1985)Doi:10.1021/jo00883a023
(1976)Doi:10.1021/jo801208m
(2008)Doi:10.1021/jo00239a043
(1988)Doi:10.1002/ejic.200700798
(2007)