Functionalization of Cyclic Structures for Advanced Biological and Pharmaceutical Applications

The key components of the scaffold in pharmaceutical chemistry are ring systems, of different sizes, and are the fundamental factors of most of the drugs on the market today. Nowadays, the importance of cyclic structures is well understood by medicinal chemists, since they play a significant role in molecular properties such as the electronic distribution, three dimensionality, and molecule rigidity. They are often key factors in whole molecule properties such as lipophilicity or polarity and can determine molecular reactivity, metabolic stability, and toxicity. Cyclic structures have always fascinated organic and medicinal chemists, and many organic molecules form cycles with appealing biological properties. Research in cyclic chemistry continued to advance in synthetic methods development, conformational studies and investigation of their role for controlling biological functions. This work, carried out in the Prof. Marcantoni’s research group at the University of Camerino (Camerino, Italy) with the collaboration of Dompé S.p.A. (L’Aquila, Italy) from December 2015 to December 2018 and in the Prof. Poli’s research group from January 2018 to July 2018 at the University Pierre and Marie Curie (Paris, France), had the objective to investigate new synthetic methodologies for the functionalization of cyclic compounds, as well as the formation of cyclic structures from acyclic precursor, for advanced biological purposes. The first chapter focuses on the functionalization of the primary face of a β-cyclodextrin, in order to obtain a synthetic human receptor model, used for studying the possible interactions of this compound with a new class of biologically active compounds in development at Dompé S.p.A. The second chapter, carried out in the Poli’s research group, describes the selective C-3 functionalization trials of 2-furaldehyde and its derivatives by Directed ortho Metalation (DoM) chemistry in presence of organolithium compounds and focuses on the study of degradation products. The reaction of an alkyllithium compound with an aromatic structure bearing a Direct Metalation Group (DMG) normally leads to an ortho-metalated intermediate. Good DMGs are strong complexing or chelating groups that have the effect of increasing the kinetic acidity of protons in the ortho position. The third chapter focuses on the in-depth study of the mechanistic aspect on the formation of 5acylaminothiazoles starting from α-chloroglycinates, obtained by a new synthetic methodology developed in the Marcantoni’s research group. Finally, the fourth chapter focuses on the study of the role of Cerium trichloride in the formation of cyclic compounds via Nazarov cyclization.