Noncovalent N-Heterocyclic Carbene Catalysis Enables Asymmetric Conjugate Addition of 2-Benzofuranones to Terminal C-Electrophiles

Herein, we report asymmetric conjugate addition of 2-benzofuranones to fully unsubstituted carbon electrophiles using noncovalent N-heterocyclic carbene (NHC) catalysis. Employing a confined chiral bifunctional NHC having a free -OH group as catalyst, the method furnishes various functionalized 2-benzofuranones bearing an all-carbon quaternary stereogenic center with broad scope, high yields, and excellent er's. Control studies suggest the concurrent activation of both partners by the bifunctional NHC.