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 [NH4](2)[Ce(NO3)(6)]. H-2[Delta-V( S,S-HIDPA)(2)].3H(2)O, H-2[Delta,Delta- V(S,S-HIDPA)(2)]. 3H(2)O and their equivalent oxidized species have been synthesized and characterized spectro scopically. A combination of COSY, NOE, H-1, C-13-NMR and CD spectroscopy h ave been used to prove that the isolated natural product Amavadin consists of an almost equal mixture of the Delta- and Delta-isomers of [V(S,S-HIDPA) (2)](2-). (C) 2000 Elsevier Science B.V. All rights reserved.