Dynamic Kinetic Resolution of Indole-Based Sulfenylated Heterobiaryls by Rhodium-Catalyzed Atroposelective Reductive Aldol Reaction

A highly enantio- and diastereoselective dynamic kinetic resolution (DKR) of configurationally labile 3-aryl indole-2-carbaldehydes is described. The DKR proceeds via a Rh-catalyzed intermolecular asymmetric reductive aldol reaction with acrylate esters, with simultaneous generation of three stereogenic elements. The strategy relies on the labilization of the stereogenic axis that takes place thanks to a transient Lewis acid–base interaction (LABI) between the formyl group and a thioether moiety strategically located at the ortho′ position. The atropisomeric indole products present a high degree of functionalization and can be further converted to a series of axially chiral derivatives, thereby expanding their potential application in drug discovery and asymmetric catalysis.