Nickel‐Catalyzed Conjugate Addition of Silyl Ketene Imines to In Situ Generated Indol‐2‐ones: Highly Enantioselective Construction of Vicinal All‐Carbon Quaternary Stereocenters

The first enantioselective conjugate addition of silyl ketene imines to in situ generated indol‐2‐ones was performed in the presence of a chiral N,N′‐dioxide/NiII catalyst. This method provides efficient access to chiral β‐alkyl nitriles bearing congested vicinal all‐carbon quaternary stereocenters in up to 90 % yield with 23:1 d.r. and 98 % ee. The products enable facile transformations to chiral pyrroloindoline frameworks and spirocyclohexane oxindole derivatives. A possible transition state was also proposed to explain the origin of the asymmetric induction.