Catalytic Enantioselective Synthesis of C 1 ‐ and C 2 ‐Symmetric Spirobiindanones through Counterion‐Directed Enolate C ‐Acylation

Abstract A catalytic enantioselective route to C 1 ‐ and C 2 ‐symmetric 2,2′‐spirobiindanones has been realized through an intramolecular enolate C‐acylation. This reaction employs a chiral ammonium counterion to direct the acylation of an in situ generated ketone enolate with a pentafluorophenyl ester. This reaction constitutes the first example of a direct catalytic enantioselective C‐acylation of a ketone and provides an efficient and highly enantioselective route to axially chiral spirobiindanediones. These products can be diastereoselectively derivatized, offering access to a range of functionalized spirocyclic architectures.