Pd(0)-Catalyzed Three-Component [2+2+1] Cycloamination to Carbazoles

Conventional approaches on using hydroxylamine derivatives as single nitrogen sources, for the preparation of N-heterocyclic molecules, rely upon two chemical operations by involving sequential nucleophilic and electrophilic C−N bond formations. Here, we report a novel Suzuki reaction/C−H activation/amination sequence for building up a myriad of carbazoles, in a single transformation, using bifunctional secondary hydroxylamines. Noteworthy, the synthetic utility of this methodology is highlighted with the total synthesis of Clausine V and Glycoborine by incorporating the titled [2+2+1] cycloamination as the key step. Control experiments were performed to gain a better understanding of the reaction mechanism.