Isolation and Structure Determination of new Iridals from Iris sibirica and Iris versicolor

Abstract Four novel iridals (compounds 8 , 11 , 12 , and 13 ), representing new examples of these unusual monocyclic triterpenoids from sword lilies, have been isolated from rhizome extracts of I. sibirica and I. versicolor . Their structures have been elucidated by spectroscopic methods combined with oxidative degradation. Based on the stereochemistry of the 10‐deoxy‐17‐hydroxyiridal 13 , the possible biosynthesis of these compounds is discussed.