Supervisors info:
Γεώργιος Βουγιουκαλάκης, Αναπληρωτής Καθηγητής, Τμήμα Χημείας, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Summary:
The research for new, alternative catalytic systems, that can replace metallic catalysts based on palladium, ruthenium, rhodium, and iridium with cheaper, more abundant, and less toxic metals such as copper, is advancing rapidly in recent years. The diversity of copper chemistry, which makes it an active catalyst, is due to its varied and interchangeable oxidation states, its ability to coordinate with heteroatoms, and its ability to activate terminal alkynes. Copper finds many applications in nitrene and carbene chemistry, [3+2] "click" reactions, cross-coupling reactions, C-H bond activation reactions, etc. The present work describes the development of two independent, copper catalyzed protocols comprising a domino reaction (Ullmann type reaction followed by a C-H bond activation) and a Sonogashira coupling reaction in the absence of palladium.
The thesis begins with the study of a new domino reaction consisting of O-H / C-H bond activation for the synthesis of aromatic molecules with important technological applications. An attempt was made to develop a copper-based catalytic system for the Ullmann-type reaction between 1,8-dihalo-naphthalene derivatives with phenols, followed by an intramolecular cyclization through C-H bond activation. This protocol has not been studied extensively and its development stopped, in the framework of the present thesis, when some first promising results were obtained.
The second part of the thesis deals with the development of a palladium-free Sonogashira reaction protocol, using an in-situ generated catalytic system obtained from a copper(I) (CuI) source and a precursor salt of a chelating 1,2,3-triazolylidene. The protocol works well at low catalytic loading, at the lowest possible cost, and provides very good Sonogashira product selectivity compared to the Glaser coupling product.
Keywords:
Sustainable catalysis, domino reaction, Ullmann reaction, C-H bond activation, Sonogashira coupling in the absence of palladium, copper, mesoionic carbenes, homogeneous catalysis
