| [2+2+1] cycloaddition reactions have been a topic of intense investigation since the discovery of what is now known as the Pauson-Khand reaction. The Pauson-Khand reaction has become a powerful reaction in organic synthesis. In the course of forming a cyclopentenone from an alkene and an alkyne, three carbon-carbon bonds are formed in one step. Studies to utilize [2+2+1] cycloaddition reactions in the synthesis of nitrogen-containing 5,5-fused bicyclic compounds as well as triquinane-like compounds will be discussed.; Dibromophakellstatin, a natural product isolated from the Indian Ocean marine sponge Phakellia mauritiana, exhibits significant antineoplastic activity. It possesses two sterogenic centers and a tetracyclic framework that encompasses a cyclic urea and an unusually stable vicinal diaminal functionality. The total synthesis of (+/-)-dibromophakellstatin will be described. The molecule is constructed from a key syn-diazide, formed by a hypervalent iodine-mediated diazidation reaction of a dihydrodipyrrolopyrazinone ring structure. |
