Polyene cyclization promoted by the cross-conjugated alpha-carbalkoxy cyclohexenone system. An unusual 1,2-hydride shift under Lewis acid catalysis.

Polyene cyclization of the titled compounds under catalysis with AlCl(3)/SnCl(4) gave rise to the corresponding polycyclic products, many of which were structurally highly unexpected, and thus, individual X-ray analysis was required to finalize the structural identification. Mechanistically, an unusual 1,2-hydride shift is proposed to elucidate the product formation.