Synthetic Studies to Fused 5/5/6‐Tricyclic Frameworks: Access to Presilphiperfolanol Analogues and A, B, C‐Ring System of Lycopodium Alkaloids and Cyclopiane Diterpenes

Abstract Herein, we describe new synthetic approaches to fused 5/5/6‐carbocyclic frameworks present in various polycyclic natural products such as presilphiperfolanols, lycopodium alkaloids, and cyclopiane diterpenes. Our work features, a strategically introduced hydroxy group at the tert ‐carbon center of the tricyclic system which is present in presilphiperfolanols. In addition, one presilphiperfolanol analogue is reported to show the potential of strategies disclosed in this work. All the new compounds are characterized by high‐resolution NMR spectral data. The structures of critical compounds were confirmed by various chemical transformations and further supported by single‐crystal X‐ray diffraction data. Overall, our approach is simple and rely on readily available starting materials and involves a tandem‐metathesis sequence. The synthetic studies disclosed here are applicable to the synthesis of natural products and to design medicinally important targets.