Enantioselective Access to Spirocyclic Sultams by Chiral Cp(x) -Rhodium(III)-Catalyzed Annulations.Chemistry. 2016 Feb 12; 22(7):2270-3.C
Chiral spirocyclic sultams are a valuable compound class in organic and medicinal chemistry. A rapid entry to this structural motif involves a [3+2] annulation of an N-sulfonyl ketimine and an alkyne. Although the directing-group properties of the imino group for C-H activation have been exploited, the developments of related asymmetric variants have remained very challenging. The use of rhodium(III) complexes equipped with a suitable atropchiral cyclopentadienyl ligand, in conjunction with a carboxylic acid additive, enables an enantioselective and high yielding access to such spirocyclic sultams.