New Catalyzed Approaches For The One-Step Synthesis Of High Value-Added Products

Abstract

Heterocyclic compounds play an important role in synthetic and bioorganic chemistry, as they represent a structural motif in a large number of biologically active natural and non-natural compounds. The synthesis of new heterocycles possessing biological activity and the development of innovative and accessible synthetic pathways are currently a very widespread research area. In the present PhD thesis is reported the development of new synthetic, simple and innovative methodologies in one step for the direct formation of high value-added compounds by the catalytic activation of simple building blocks, CO and CO2. CO is a simplest and most available C-1 unit, which meets the requirements of “atom economy”, step economy and “green chemistry”; the possibility to synthesize molecules of important pharmacological interest by a direct carbonylation procedure involving the use of carbon monoxide represent a very attractive alternative synthetic approach. CO2 is the main component of greenhouse gases, responsible for the increase in the earth's temperature and anomalous climate changes. Thus, post-combustion COIn fact, carbon dioxide can be considered as a ubiquitous, cheap, abundant, non-toxic, non-flammable and renewable C1 source, which has great importance from the viewpoint of both environmental protection and resource utilization. In the first chapter is reported a new example of an additive cyclocarbonylation process leading to 1-thia-4a,9-diazafluoren-4-ones, an important class of polyheterocyclic compounds known to possess important pharmacological activities. Part of this PhD was spent at Leibniz Institute for Catalysis in Rostock University. Here, ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. The advantages of the new catalysts are demonstrated in the general green α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Furthermore, other cyclometalated ruthenium complexes bearing bidentate ligand were obtained for methylation of anilines with methanol to selectively give N-methylanilines. The hydrogen autotransfer procedure has been applied under mild conditions (60 °C) in a practical manner (NaOH as base).2 capture and its conversion into high value-added chemicals are integral parts of today’s green energy industry.