NMR studies on natural and synthetic Amavadin.

The stereochemistry of isolated natural product Amavadin, which contains a 1:2 complex of V(IV) with N-hydroxyimino-2,2'-dipropionic acid (HIDPAH(3)), and some synthetic complexes have been investigated. Amavadin was isolated from Amanita muscaria and oxidized with [NH(4)](2)[Ce(NO(3))(6)]. H(2)[Delta-V(S,S-HIDPA)(2)].3H(2)O, H(2)[Delta,Lambda-V(S,S-HIDPA)(2)].3H(2)O and their equivalent oxidized species have been synthesized and characterized spectroscopically. A combination of COSY, NOE, (1)H, (13)C-NMR and CD spectroscopy have been used to prove that the isolated natural product Amavadin consists of an almost equal mixture of the Delta- and Lambda-isomers of [V(S,S-HIDPA)(2)](2-).