Synthesis of Carbazoles by Copper-Catalyzed Intramolecular C–H/N–H Coupling
摘要:
A Cu-catalyzed intramolecular C-H amination for the synthesis of carbazoles has been developed. The key to success is the installation of the picolinamide-based directing group, which is spontaneously removed after the coupling event. The Cu catalysis proceeded smoothly under Pd- and I(III)-free conditions, and its mild oxidation aptitude enables the rapid and concise construction of heteroatom-incorporated carbazole core pi-systems.
A traceless directing group assisted Co-catalyzed C(sp2)–H carbonylation of ortho-arylanilines for the synthesis of free (NH)-phenanthridinones in metal-based-oxidant-free fashion was accomplished. This protocol employs diisopropyl azodicarboxylate as the CO source and oxygen as the sole oxidant, and provides good yields with various functional tolerance. The methodology has been applied for the total
CoCl2‐catalyzed formal [5+2] oxidative annulation of o‐arylanilines with alkynes was developed, giving access to various important imine‐containing dibenzo‐[b,d]azepine scaffolds through sequential C−C/C−N bond formation. The reaction employs catalytic amount of manganese and oxygen as cooxidants, and features a broad substrate scope. Preliminary mechanistic studies suggested that C−Hactivation is involved