Base-catalyzed Tandem Reaction Of α,α-Dicyanoolefins With Electron-Deficient1,3-Conjugated Enynes

The development of tandem reactions for rapid access to complex molecules with multiple stereogenic centres has attracted considerable attention in both academic and industrial research. Angularly fused carbocyclic frameworks and their heteroatom-substituted analogues exist in many natural products which display a broad range of interesting biological activities. One of the challenges in the synthesis of these natural products and their analogues is usually related to exploring one tandem reaction to construct these polycyclic skeleton sharing with a quaternary carbon atom and bearing multiple consecutive stereogenic carboncenter.Dehydro-Diels-Alder (DDA) reactions are one class of dehydropericyclic reactions which are derived conceptually by systematic removal of hydrogen atom pairs. In past years, the DDA reactions occuring between enynes, arylalkynes, and alkynes leading to benzenes or naphthalenes have been extensively studied, but DDA reactions between enynes or arylalkynes with olefins leading to dihdrobenzenes or1,2-dihydronaphthalenes have not been well studied and the scope of olefins is often limited to electron-rich olefins. On the other hand, despite the fact that the DDA reaction has been discovered for more than a century, there is still an ongoing debate in the scientific community on the reaction mechanism, that is, via the concerted1,5-hydrogen shift or stepwise anionic mechanism.Herein, we investigated that a base-promoted tandem Michael addition and DDA reaction of α, α-dicyanoolefins with electron-deficient1,3-conjugated enynes, in which DDA reaction takes place between the arylalkynes and electron-deficient tetrasubstituted olefin and control experiments support the reaction is a stepwise anionic reaction pathway.