posted on 2021-04-23, 17:33authored byJingjun Huang, Matthew Isaac, Ryan Watt, Joseph Becica, Emma Dennis, Makhsud I. Saidaminov, William A. Sabbers, David C. Leitch
We report an easily prepared and
bench-stable mononuclear Pd(0)
source stabilized by a chelating N,N′-diaryldiazabutadiene ligand and maleic anhydride: DMPDAB–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. DMPDAB–Pd–MAH
itself is readily soluble and stable in several organic solvents,
making it an ideal Pd source for in situ catalyst
preparation during reaction screening as well as solution-dispensing
to plate-based reaction arrays for high-throughput experimentation.
Evaluation of DMPDAB–Pd–MAH alongside other
common Pd(0) and Pd(II) sources in microscale reaction screens reveals
that DMPDAB–Pd–MAH is superior at identifying
hits across six different C–N, C–C, and C–O coupling
reactions. DMPDAB–Pd–MAH, and the phosphine
precatalysts derived therefrom, are also effective in preparative-scale
cross-couplings at low Pd loadings.