Alkene-Coordinated Palladium(0) Cross-Coupling Precatalysts: Comparing Oxidative Addition and Catalytic Reactivity for Dimethyl Fumarate and Maleic Anhydride Stabilizing Ligands

Air-stable palladium(0) precatalysts are advantageous for facilitating a variety of chemical transformations and are desirable precursors for high-throughput experimentation studies. We report investigations into air-stable Pd(0) precatalysts stabilized by dimethyl fumarate (DMFU) as an electron-deficient alkene. A Pd(0) DMFU complex with a diazabutadiene (DAB) supporting ligand readily undergoes substitution with both monodentate and bidentate phosphines to form phosphine–Pd–DMFU complexes in situ. These complexes undergo oxidative addition with ArBr substrates and are also effective precatalysts for Heck coupling, Suzuki–Miyaura coupling, and Miyaura borylation. Catalytic comparisons of the DAB–Pd–DMFU precursor to other Pd sources reveals benefits and limitations of this system, including high activity in Heck coupling, and challenges with in situ catalyst generation.