Mechanistic Study on Pd/Mono-N-protected Amino Acid Catalyzed Vinyl-Vinyl Coupling Reactions: Reactivity and E/Z Selectivity

摘要

A combined mass spectrometric and computational study of the Pd/mono-N-protected amino acid (MPAA)-catalyzed vinyl-vinyl coupling reactions is reported. Computational study reveals that the reaction is initiated by C-H activation of the styrene followed by the insertion of acrylate. This is supported by mass spectrometry. The MPAA ligand facilitates the cross-coupling reaction between monosubstituted alkenes by stabilizing the active palladium catalyst and offering the N-protecting group as a stronger base than acetate. The E/Z selectivity is attributed to the stronger d-pi interaction between the catalyst and the substrate in the transition state leading to E product.