EvanPhos: a ligand for ppm level Pd-catalyzed Suzuki–Miyaura couplings in either organic solvent or water†
A new biaryl phosphine-containing platform can be constructed in only two steps. It complexes Pd(OAc)2 forming a precursor of a very active catalyst useful for Suzuki–Miyaura cross-couplings of functionalized substrates. By a combination of pre-activation, used together with the uncommon solvent EtOAc, the resulting catalyst system is effective at loadings in the ppm (0.1–0.5 mol%) range with highly functionalized reaction partners. Similar reactions run in water containing nanomicelles are as fast or faster. The derived Pd-complexed pre-catalyst possesses extended bench stability. The resulting technology represents an attractive green synthetic advance in highly valued Suzuki–Miyaura couplings.