The urea renaissance

Over the last decade the use of urea derivatives as useful reagents, catalysts, and structural features in organic chemistry has increased rapidly. They now find utility as hydrogen-bond donors in organocatalysts and anion transporters, as important scaffolds in supramolecular chemistry, as lithiation directors, amination substrates, and promoters of metalation, and as substrates for novel rearrangement reactions. Highlighted herein is the remarkably rapid and recent development of the chemistry of ureas, which for many years had been considered unreactive, intractable, and of little value. It's back: This Minireview summarizes the development of urea chemistry during the last few years by taking examples to illustrate each of the themes associated with this renaissanceâureas as lithiation directors, the design of urea-based catalysts and supramolecular structures, the increased reactivity that is characteristic of more hindered ureas, and the electrophilicity disguised within electron-rich aromatic ureas (see picture).