Insights on Bimetallic Micellar Nanocatalysis for Buchwald-Hartwig Aminations

A nanocatalyst for micellar Buchwald-Hartwig aminations is developed, thoroughly characterized, and applied on a variety of substrates. The catalyst is stable under ambient conditions for at least six months. The catalyst retained its activity after several cycles, and its structure remained intact as confirmed by NMR spectroscopy. Association of Pd nanoparticles with Cu by a phosphine ligand is revealed by P-31 NMR spectroscopy, and their linkage with the activated carbon surface is revealed by XAS analysis. Control NMR experiments revealed the binding of the ligand with both Cu and Pd, and all phosphine molecules are under the same environment. In addition to NMR and XAS analysis, the catalyst is characterized by SEM, HRTEM, XPS, and TGA. Reactions are highly reproducible at variable scales. Environmentally benign, proline-based amphiphile PS-750-M is critical for catalytic activity, which is achieved under mild conditions in water as the reaction medium. The inherent sustainability of these conditions coupled with a low E factor achievable through robust recycling of catalyst and reaction medium demonstrates the significant utility of this technology.