Phytotoxic compounds produced by Fusarium equiseti. Part 7. Reactions and rearrangement of the 7-hydroxy-12,13-epoxytrichothec-9-en-8-one skeleton

Abstract

7α,15-Dihydroxy-12,13-epoxytrichothec-9-en-8-ones, e.g. nivalenol and vomitoxin, rearrange under mild basic conditions to the isomeric 7,13-epoxy-A-nortrichothecane-7-carboxylic acid 15-lactones. With hydrogen chloride, normal addition to the 12,13-epoxide of these compounds occurs, with retention of configuration at C-12, and the more usual rearrangement to the 2β-chloroapotrichothec-9-en-8-one skeleton is not seen. Catalytic hydrogenation of diacetylnivalenol takes place from the β-face to give the corresponding (9R)-trichothecan-8-one. Reliable procedures for the preparation of vomitoxin and nivalenol from their acetates are outlined.