ChemInform Abstract: Structure Determination of New Iridals from Iris pallida and Iris foetidissima.

Abstract

The four novel iridals 8-10 and 18 were isolated from rhizome extracts of Irispallida and Irisfoetidissima, and their structures were established by spectroscopic methods and oxidative degradation. The compounds 8-10 bearing a conjugated triene moiety are extremely labile and decompose rapidly. Thus, the monocyclic triene 8 was only isolated after its conversion to a Diels-Alder adduct with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (14). The tricyclic iridal18 is a hitherto unknown precursor of ct -irone. The possible biogenesis of these unusual triterpenoids is discussed.