PhD student, Hengmu Xie presents Sequential Enantioselective Iridium-Catalyzed Allylic Alkylation/Cope Rearrangement for Construction of Acyclic γ-Stereocenters

Ph.D. Seminar Title

Sequential Enantioselective Iridium-Catalyzed Allylic Alkylation/Cope Rearrangement for Construction of Acyclic γ-Stereocenters

The catalytic asymmetric functionalization of carbonyl derivates at the remote γ-position is challenging because of the issues with controlling chemo- (O vs. C), regioselectivity (α vs. γ), and enantioselectivity at a remote position.  In recent years, enantioselective transition metal-catalyzed γ-allylic alkylation reactions have attracted increasing attention, albeit they are typically restricted to cyclic pronucleophiles.  A general strategy to regio- and stereoselectively produce acyclic γ-allylic substituted carbonyl derivates is underdeveloped, especially for constructing quaternary stereocenters.  The seminar will outline the development of two enantioselective iridium-catalyzed γ-allylic alkylation of acyclic nucleophiles to address this challenging problem.  This work efficiently combines an enantioselective iridium-catalyzed allylic alkylation with a stereospecific Cope rearrangement.  Additionally, these reactions are remarkably tolerant of a range of acyclic substituents, and the synthetic utility is demonstrated through conversion towards a series of related carbonyl derivatives that contain acyclic β- and γ-tertiary and quaternary stereocenters.