Selective demethylation of some aconitine-type norditerpenoid alkaloids

Journal of Natural Products
B S JoshiS W Pelletier

Abstract

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 (1H, 13C, 1H 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.

Citations

Jan 19, 2012·Journal of Asian Natural Products Research·Yong ShenJi-Jun Chen
May 16, 2012·Journal of Asian Natural Products Research·Xue-Ke SheFeng-Peng Wang
Nov 13, 2015·Journal of Asian Natural Products Research·Yan QiYong Shen
Mar 24, 2018·Journal of Asian Natural Products Research·Wang-Yan LiuYong Shen
Apr 23, 2011·Molecules : a Journal of Synthetic Chemistry and Natural Product Chemistry·Ning XuYuan-Sheng Xiao
Sep 14, 2002·Experimental Aging Research·Douglas C Ewbank
Nov 13, 2018·Journal of Asian Natural Products Research·Dan HeYong Shen
Mar 10, 2017·Journal of Asian Natural Products Research·Gui-Qiong LiYong Shen
Apr 28, 1999·Journal of Natural Products·X FuG C Williams

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