Development of Transition-Metal-Catalyzed Transformations of Triazoles

This thesis defense presentation describes the development of transition-metal-catalyzed transformations of fused pyridotriazoles, as well as monocyclic N-sulfonyl-1,2,3-triazoles, which allows efficient synthesis of various valuable nitrogen-containing compounds. One major focus of Part I lies in subsequent section describing the development of a general and efficient rhodium-catalyzed reaction of pyridotriazoles with amides and amines, allowing facile synthesis of valuable picolylamine derivatives, providing expeditious access to various disubstituted imidazopyridines in a one-pot manner via the subsequent cyclization. With this method, we broke the structural limitation of pyridotriazoles (activating group at C7-position, EWG at C3-position). Moreover, the imidazopyridines obtained with this protocol are not accessible by previously reported transannulation reaction of pyridotriazoles with nitriles. Another focus of Part I is the discovery of copper-catalyzed intramolecular transannulation reaction of pyridotriazoles with internal alkynes, offering efficient construction of various tri-, tetra-, and pentacyclic fused indolizines. It is not only the first intramolecular transannulation reaction of pyridotriazoles, but also for the first time it is shown that this reaction could also be triggered by Lewis acids. In Part II, we developed a method for expeditious access to various 5,5-fused pyrroles from easily available N-sulfonyl-1,2,3-triazoles. Moreover, it can also be used to efficiently construct spiro systems, as well as fused tetrahydropyrrolo-pyrrole cores. In contrast to previously reported methods where ylides are key intermediates, preliminary mechanistic study reveals that a Rh-carbene-alkyne metathesis step is involved in this transformation.