Metal-Free N-H/C-H Carbonylation by Phenyl Isocyanate: Divergent Synthesis of Six-Membered N -Heterocycles.

We disclose a method using phenyl isocyanate to synthesize carbonyl-containing N -heterocycles. The metal-free novel approach for both N-H and C-H carbonylation processes was successfully refined, delivering a range of synthetically valuable derivatives of quinazoline-2,4(1 H ,3 H )-dione, 2 H -benzo[ e ] [1,2,4] thiadiazin-3(4 H )-one 1,1-dioxide, and pyrrolo[1,2- a ] quinoxalin-4(5 H )-one. The protocol features broad substrates with diverse reactions suitable for excellent yields, mild conditions, and good functional group compatibility. Moreover, the applicability of the reaction was characterized by gram-scale synthesis and synthetic transformations for drug molecules.