Internal Lewis acid assisted ureas: tunable hydrogen bond donor catalystsThis article is part of the ChemComm 'Emerging Investigators 2013' themed issue.Electronic supplementary information (ESI) available: Detailed experimental procedures and characterization data. CCDC 903666 (platinacycle) and 882366 (palladacycle). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2cc37073e

The strategic incorporation of internal Lewis acids onto urea scaffolds gives rise to a family of tunable hydrogen bond donor catalysts. The nature of the Lewis acid and associated ligands affects the urea polarization, acidity, and activity in reactions of nitrocyclopropane carboxylates and nitrodiazoesters. The strategic incorporation of Lewis acids on urea scaffolds yields tunable hydrogen bond donor catalysts benefiting from enhanced activity.