NMR studies on natural and synthetic amavadin.

Abstract 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 [Δ-V( S,S -HIDPA) 2 ].3H 2 O, H 2 [Δ,Λ-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 Δ- and Λ-isomers of [V( S,S -HIDPA) 2 ] 2− .