Catalytic Enantioselective Synthesis of C1 - and C2 -Symmetric Spirobiindanones through Counterion-Directed Enolate C-Acylation.

A catalytic enantioselective route to C1 - and C2 -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.