Palladium-Catalyzed Asymmetric Cycloaddition/Cope Rearrangement Relay: Synthesis of Chiral Endocyclic Allenes

Abstract

AbstractThe synthesis of chiral endocyclic allenes, especially the medium-sized ones, remains a challenge in allene chemistry due to unfavorable tension and difficult stereocontrol. Herein, an efficient protocol for the construction of chiral nine-membered endocyclic allenes via palladium-catalyzed asymmetric cycloaddition/Cope rearrangement relay of vinyl carbonates with activated enynes is highlighted. This process provides rapid access to a variety of chiral nine-membered endocyclic allenes in good yields with excellent enantioselectivities. In particular, a chiral P,S-ligand shows good performance on stereoinduction, generating central and axial chirality in a single transformation, which is rationalized by DFT calculations and by a proposed transition state.1 Introduction2 Pd-Catalyzed Asymmetric Cycloaddition/Cope Rearrangement Relay3 Plausible Mechanism and Stereochemical Outcome4 Conclusion and Outlook