FeCl3-Catalyzed Highly Efficient Nazarov Type Cyclization of Arylvinyl Carbinols: Total Syntheses of Naturally Occurring Taiwaniaquinoids

Résumé fourni par la source

FeCl3-catalyzed cyclization of arylvinylcarbinols for the synthesis of [6,5,6]-carbotricyclic core sharing an all-carbon quaternary center has been described in this full article. A careful mechanistic details suggest that the reaction follows a stepwise mechanism via the intermediacy of arylallyl carbocationic species. The carbocation subsequently reacts with an adjacent aromatic ring to form [6,5,6]-carbotricyclic scaffold of abeo-abietane diterpenoids. The methodology works under mild conditions to afford a variety of carbotricyclic core in good to excellent yields (up to 99% yield). Our strategy has been applied to a concise synthesis of a number of structurally intriguing naturally occurring taiwaniaquinoids, (±)-taiwaniaquinol F (1a), (±)-taiwaniaquinol B (1b), (±)-dichronanone (1c), (±)-taiwaniaquinone H (1d) and unnatural (±)-5-epi-taiwaniaquinone G (epi-1e).

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