A review that highlights water as the logical reaction medium in which organic chemistry can be practiced. The key roles that water can play in directing reaction outcomes, including impacting mechanistic features, are discussed using selected examples.

Powdery, spherical nanoparticles (NPs) containing ppm levels of palladium ligated by t-Bu 3 P, derived from FeCl 3 , upon simple exposure to water undergo a remarkable alteration in their morphology leading to nanorods that catalyze Mizoroki−Heck (MH) couplings. Such NP alteration is general, shown to occur with three unrelated phosphine ligand-containing NPs. Each catalyst has been studied using X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and cryogenic transmission electron microscopy (cryo-TEM) analyses. Couplings that rely specifically on NPs containing t-Bu 3 P-ligated Pd occur under aqueous micellar catalysis conditions between room temperature and 45 °C, and show broad substrate scope. Other key features associated with this new technology include low residual Pd in the product, recycling of the aqueous reaction medium, and an associated low E Factor. Synthesis of the precursor to galipinine, a member of the Hancock family of alkaloids, is suggestive of potential industrial applications.