We report an easily prepared and bench-stable
mononuclear Pd(0) source stabilized by a chelating <i>N</i>,<i>N</i>’-diaryldiazabutadiene
ligand and maleic anhydride: <sup>DMP</sup>DAB–Pd–MAH. Phosphine ligands of all
types, including bidentate phosphines and large cone angle biarylphosphines,
rapidly and completely displace the diazabutadiene ligand at room temperature
to give air-stable Pd(0) phosphine complexes. <sup>DMP</sup>DAB–Pd–MAH itself
is readily soluble and stable in several organic solvents, making it an ideal
Pd source for <i>in situ</i> catalyst
preparation during reaction screening, as well as solution-dispensing to
plate-based reaction arrays for high-throughput experimentation. Evaluation of <sup>DMP</sup>DAB–Pd–MAH
alongside other common Pd(0) and Pd(II) sources in microscale reaction screens
reveals that <sup>DMP</sup>DAB–Pd–MAH is superior at identifying hits across
six different C–N, C–C, and C–O coupling reactions. <sup>DMP</sup>DAB–Pd–MAH,
and the phosphine precatalysts derived therefrom, are also effective in
preparative-scale cross couplings at low Pd loadings.
Cover Feature: In Situ Generation of Ruthenium Carbonyl Phosphine Complexes as a Versatile Method for the Development of Enantioselective C−O Bond Arylation (Chem. Eur. J. 8/2020)
