New sesquiterpenes from Ferula ferulaeoides (Steud.) Korovin. VI. Isolation and identification of three new dihydrofuro[2,3-b]chromones

Three novel 2-prenyl-dihydrofurochromone-type sesquiterpenoid derivatives, 2,3-dihydro-7-hydroxy-2S*,3R*-dimethyl-2-4,8-dimethyl-3(E),7-nonadienyl]-furo2,3-b]chromone, 2,3-dihydro-7-hydroxy-2S*,3R*-dimethyl-2-4-methyl-5-(4-methyl-2-furyl)-3(E),7-pentenyl]-furo2,3-b]chromone, and 2,3-dihydro-7-hydroxy-2R*,3R*-dimethyl-2-4-methyl-5-(4-methyl-2-furyl)-3(E),7-pentenyl]-furo2,3-b]chromone, were isolated from the roots of Ferula ferulaeoides. The structures were established by comprehensive spectral analysis. The biosynthetic pathway leading to these 2-prenyl-dihydrofurochromone-type sesquiterpenoids is proposed based on their structures.