Design and Synthesis of Linearly Fused Triquinanes through Tandem‐Metathesis: Access to Basic Core of Cucumin, Capnellene, Chondrosterin, and Xeromphalinone

Herein, a short synthetic approach to linearly fused tricyclic enone 1 and cis‐anti‐cis type hydroxy‐triquinane 2 has been described in an efficient manner by employing tandem‐metathesis as a key step. The triquinane‐based enone 1 is prepared by a Babler–Dauben oxidation of hydroxy‐triquinane 2, which is assembled by following a three‐step sequence involving a regio‐ and stereoselective allylation, vinyl Grignard addition, and tandem‐metathesis. Our strategy relies on exo‐tricyclic ketone, which is derived from readily available exo‐dicyclopentadiene‐1‐one. The newly synthesized molecules were identified and characterized by nuclear magnetic resonance spectroscopy (NMR), and high‐resolution mass spectrometry (HRMS) data. It is worth mentioning that tricyclic enone 1 is present as a core unit of many naturally occurring polyquinanes, particularly xeromphalinone family members. Hence, our approach may be useful in the synthesis of such bioactive molecules. A tandem‐metathesis approach to linearly fused tricyclic enone 1 and cis‐anti‐cis‐type hydroxy‐triquinane 2 has been described in an efficient manner starting with exo‐dicyclopentadiene‐1‐one. The tricyclic enone 1 was found to be a core unit of triquinane‐based natural products such as cucumin, capnellene, chondrosterin, and xeromphalinone.