Pyrazole-tethered arylphosphine ligands for Suzuki reactions of aryl chlorides: How important is chelation?

Article abstract of DOI:10.1016/j.tetlet.2004.11.016

Pyrazole-derived bidentate ligands (P,N-donor) with bulky substituents at the 3-position of the pyrazole, 1b-d, were used with Pd₂(dba) ₃ to carry out efficient Suzuki coupling reactions with both aryl bromides and chlorides. Enhanced catalytic activity on account of steric crowding in the metal complex suggested participation of a chelated structure in the intermediate catalytic steps.