Various monosubstitution and disubstitution patterns on the parent biarylamine skeleton characteristic of palladacycles, as well as the counterion effect, have been studied while looking for ways to increase the effectiveness of the catalyst formed under micellar catalysis conditions in water, with the goal of reducing the amount of Pd needed for coupling reactions. Several substituted palladacycles containing readily accessible ligands were chosen for evaluation. The results indicate that (1) preactivation of Pd­(II) salts as precursors for Suzuki–Miyaura (SM) couplings via treatment with a reducing agent is not required; (2) reactions could be performed with approximately half the loading of Pd, relative to that previously required based on a combination of a Pd­(II) salt and ligand; and (3) the most effective palladacycle precatalyst has been identified as that containing an isopropyl group on both an aryl ring and on nitrogen, together with the ligand EvanPhos and triflate as the counterion (P13). This precatalyst is also effective in other C–C bond-forming reactions, such as Heck and Sonogashira couplings. No organic solvents were needed for these processes, while the aqueous reaction medium could be recycled several times. A one-pot, four-step sequence involving Suzuki–Miyaura, reduction, alkylation, and acylation reactions highlights the potential for this precatalyst to maximize synthetic gain while minimizing costs and waste generation.

Condensation in recyclable water between aldehydes or ketones and amines occurs smoothly within the hydrophobic cores of nanomicelles, resulting in imine formation that is subject to subsequent reduction leading, overall, to reductive amination. This micellar technology enables the synthesis of several types of pharmaceuticals, a new procedure that relies on only 2000 ppm (0.20 mol %) palladium from commercially available Pd/C. A broad range of substrates can be used under mild conditions, leading to high chemical yields of the desired secondary and tertiary amines.

A new, biaryl phosphine-containing ligand, N2Phos, forms a 1 : 1 complex with Pd resulting in an active catalyst at the ppm level for Suzuki–Miyaura couplings in water, enabled by an aqueous micellar medium. Notably, aryl chlorides are shown to be amenable substrates.