Reduction of Furanoheliangolides

Substrates containing oxygenated functions at C15 (such as 1, 5 and 6) gave also some products of reduction of the α,β,γ, -unsaturated furanone, but eremantholides were always obtained with yields between 30 to 50% in all cases of scheme 1. However, when we treated budlein A (2) with Stryker’s reagent under the same conditions, no eremantholide was formed at all. As shown is scheme 2, only reduced products were formed, and no cyclization occurred. Scheme 2.