Multicatalytic, asymmetric Michael/Stetter reaction of salicylaldehydes and activated alkynes

We report the development of a multicatalytic, one-pot, asymmetric Michael/Stetter reaction between salicylaldehydes and electron-deficient alkynes. The cascade proceeds via amine-mediated Michael addition followed by an N-heterocyclic carbene-promoted intramolecular Stetter reaction. A variety of salicylaldehydes, doubly activated alkynes, and terminal, electrophilic allenes participate in a one-step or two-step protocol to give a variety of benzofuranone products in moderate to good yields and good to excellent enantioselectivities. The origin of enantioselectivity in the reaction is also explored; E/Z geometry of the reaction intermediate as well as the presence of catalytic amounts of catechol additive are found to influence reaction enantioselectivity.