ppm Pd-Containing Nanoparticles as Catalysts for Negishi Couplings in Water.

New technology is reported that enables Negishi couplings to be run under sustainable, far greener conditions. Thus, ppm Pd-containing nanoparticles (NPs) have been developed that catalyze couplings in recyclable water under very mild conditions. These heterogeneous reactions involve loadings of Pd of typically only 2500 ppm (0.25 mol %). Highly functionalized aromatic and heteroaromatic bromides readily participate, including examples taken from the Merck Informer Library indicative of the functional group tolerance associated with these couplings. Direct comparisons with existing literature routes are made. Very low residual levels of Pd in newly formed products are to be expected, as determined by ICP-MS. The reagent involved has been extensively characterized via DLS, TEM, cryo-TEM, and EDX measurements.