Bimetallic Catalytic Tandem Reaction of Acyclic Enynones: Enantioselective Access to Tetrahydrobenzofuran Derivatives.

A highly efficient enantioselective synthesis of multisubstituted tetrahydrobenzofuran derivatives with four contiguous stereocenters was established by the dual catalysis of a gold(I)/chiral N,N'-dioxide-cobalt(II) complex via a tandem cycloisomerization/Diels-Alder reaction of 2-alkynyl-2-alkenones and electron-deficient olefins. This strategy was not only featured with atom economy, remarkable efficiency and stereoselectivity but also was highlighted by further transformations of the furan-based products into polycyclic molecules. Moreover, a possible transition-state model was proposed to elucidate the origin of stereoselectivity.