Interrogating Pd(II) Anion Metathesis Using a Bifunctional Chemical Probe: A Transmetalation Switch

Ligand metathesis of Pd­(II) complexes is mechanistically essential for cross-coupling. We present a study of halide→OH anion metathesis of (Ar)­PdII complexes using vinyl­BPin as a bifunctional chemical probe with Pd­(II)-dependent cross-coupling pathways. We identify the variables that profoundly impact this event and allow control to be leveraged. This then allows control of cross-coupling pathways via promotion or inhibition of organoboron transmetalation, leading to either Suzuki–Miyaura or Mizoroki–Heck products. We show how this transmetalation switch can be used to synthetic gain in a cascade cross-coupling/Diels–Alder reaction, delivering borylated or non-borylated carbocycles, including steroid-like scaffolds.