Acyclic Quaternary Stereocenters via Catalytic Asymmetric Cross-Couplings with Unactivated Alkyl N-Hydroxyphthalimide Esters.

While significant advancements have been made in creating quaternary stereocenters (all-carbon substituents) within cyclic frameworks, generating acyclic quaternary stereocenters poses a more formidable task due to increased conformational flexibility. Herein, we report an enantioselective synthesis of compounds containing acyclic quaternary stereocenters through an iron-catalyzed alkylation reaction between an acyclic tertiary alkyl source and an unactivated primary alkyl source. This method not only facilitates the rapid construction of sterically hindered motifs but also effectively enhances the saturation level of the molecule. Key to this method is an outer-sphere C─C bond formation mechanism, where enantioselectivity is governed by a cooperative triple catalysis system that combines photoredox, chiral Lewis acid, and iron catalysis. A series of compounds featuring acyclic quaternary stereocenters is produced under mild reaction conditions, and various transformations are presented to illustrate the potential applications of this approach. A comprehensive mechanistic study supports the crucial S2 (bimolecular homolytic substitution) mechanism.