Catalytic Dealkylative Synthesis of Cyclic Carbamates and Ureas via Hydrogen Atom Transfer and Radical-Polar Crossover

Guided by the transition metal hydrogen atom transfer and radical-polar crossover concept, we developed a catalytic, Markovnikov-selective, functional-group tolerant, and scalable synthesis of cyclic carbamates, which are found in the structures of many bioactive compounds. This method not only provides common oxazolidinones but also six-to-eight-membered ring products. The reaction proceeds through the intramolecular displacement of an alkylcobalt(IV) in-termediate and dealkylation by 2,4,6-collidine; the activation energies of these steps were calculated by DFT. Cyclic ureas and cyclic phosphoramidates were also synthesized under the same reaction conditions.