A facile synthesis of bridged-tricyclic skeletons via intramolecular Diels-Alder reaction of cyclic 1,3-dienes containing an α,β- unsaturated ester

Intramolecular Diels-Alder reaction (IMDA) precursors are easily available starting from addition of ester functionalized zinc-copper reagents to cyclohexadienyl- and cycloheptadienylirontricarbonyl cation salts. The resulting cyclic 1,3-dienes containing an α,β-unsaturated ester functionality underwent smoothly IMDA reaction to afford bridged tricyclic compounds. Bridged heterotricyclic skeletons were also available via IMDA reaction of cyclic 1,3-dienes bearing an imine or aldehyde functionality.