Selective demethylation of some aconitine-type norditerpenoid alkaloids

被引:24
作者
Joshi, BS [1 ]
Srivastava, SK [1 ]
Barber, AD [1 ]
Desai, HK [1 ]
Pelletier, SW [1 ]
机构
[1] UNIV GEORGIA,DEPT CHEM,ATHENS,GA 30602
来源
JOURNAL OF NATURAL PRODUCTS | 1997年 / 60卷 / 05期
关键词
D O I
10.1021/np9606862
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
Demethylation of some aconitine-type norditerpenoid alkaloids was carried out with trimethylsilyl iodide and with HBr in glacial AcOH. Aconitine (10), cammaconine (23), delphinine (3), falconerine (18), lappaconitine (22), and talatizamine (24) afforded partially demethylated products. When methoxyl groups are present at the C-16 and C-18 positions, these are demethylated, and the methoxyl group at the C-1 position underwent demethylation in none the alkaloids studied except falconerine (18). With HBr-AcOH, in the case of alkaloids possessing a C-3 hydroxyl group, the methoxymethyl at C-18 formed a tetrahydrofuran, cyclizing at the C-6 position. Detailed NMR spectral studies (H-1, C-13, H-1 homonuclear COSY, HETCOR, and selective INEPT) carried out on the demethylation products have enabled accurate chemical shift assignments to be made for the demethylated alkaloids.
引用
收藏
页码:439 / 443
页数:5
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