A simple and efficient strategy towards eleven-membered carbocycles via novel synthetic transformations of pentafulvenes

A novel and versatile method towards the synthesis of eleven-membered carbocycles through a three step reaction sequence from pentafulvenes is described. The [6+3] adduct of pentafulvenes with 3-oxidopyrylium betaine on selective reduction followed by ruthenium catalyzed oxidative cleavage afforded a novel eleven-membered carbocyclic triketone with a bridging ether linkage. The methodology described herein is easy to perform and delivers densely functionalized carbocycles in good yields. The procedure is noteworthy as it hardly requires an elaborated catalytic system and proceeds with high level of atom efficiency from cheap and easily available starting materials. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)