Four‐Step Synthesis of (−)‐4‐<i>epi</i>‐Presilphiperfolan‐8<i>α</i>‐ol by Intramolecular Iron Hydride Atom Transfer‐Mediated Ketone‐Alkene Coupling and Studies to Access <i>trans</i>‐Hydrindanols with a Botryane Scaffold
Mar Saladrigas, Enrique Gómez‐Bengoa, Josep Bonjoch, Ben Bradshaw
Abstract
Abstract From an ( R )‐(+)‐pulegone‐derived building block that incorporates the stereo‐defined tertiary carbon bearing a methyl group, as found in the targeted sesquiterpenoid, a four‐step synthesis of (−)‐4‐ epi ‐presilphiperfolan‐8‐ α ‐ol was achieved. The key processes involved are a ring‐closing metathesis leading to a bridged alkene‐tethered ketone and its subsequent Fe III ‐mediated metal‐hydride atom transfer (MHAT) transannular cyclization. This synthetic method, implying an irreversible addition of a carbon‐centered radical upon a ketone by means of a hydrogen atom transfer upon the alkoxy radical intermediate, was also applied in the synthesis of trans ‐fused hydrindanols structurally related to botrydial compounds.