Toward the Total Synthesis of Sesquiterpene via an Annulative and Oxidative Approach

The phenolic sesquiterpene (±)-jungianol, originally isolated from Jungia malvifolia (family Asteraceae), has previously been targeted through various synthetic approaches. However, none of these methods have successfully produced (±)-jungianol as the major product, largely due to difficulties in synthesizing trans-1,3-substituted indane frameworks. Herein, we present an annulative strategy for the total synthesis of (±)-jungianol, emphasizing several key transformations, including olefination via Wittig and Grignard reactions, hydrogenation, iodination, cross-coupling reactions, oxidation, acetylation, and hydrogenolysis of the acetylated product. Most notably, this study explores the use of a ring contraction reaction, particularly for the formation of trans-1,3-substituted indanes, structural motifs essential to (±)-jungianol via an environmentally friendly iodine-(III) reagent. Efforts are underway to synthesize the targeted natural product, which is just one step away from our synthesized trans-indane intermediate.