Formamides as Isocyanate Surrogates: A Mechanistically-Driven Approach to the Development of Atom-Efficient, Selective Catalytic Syntheses of Ureas, Carbamates and Heterocycles

Despite the hazardous nature of isocyanates, they remain key building blocks in bulk and fine chemical synthesis. By surrogating them with less potent and readily available formamide precursors, we herein demonstrate an alternative, mechanistic approach to selectively access a broad range of ureas, carbamates and heterocycles via a ruthenium-based pincer complex catalyzed acceptorless dehydrogenative coupling reactions. The design of these highly atom-efficient procedures was driven by the identification and characterization of the relevant organometallic complexes, uniquely exhibiting the trapping of an isocyanate intermediate. DFT calculations further contributed to shed light on the remarkably orchestrated chain of catalytic events, involving metal-ligand cooperation.