The thesis focuses on the development of new methodologies for the selective functionalization of complex molecules, with potential applications in medicinal chemistry and drug discovery. New C-B, C-C and C-N bond formation is achieved via different strategies, covering both the fields of diborylation and iridium-catalysed selective transformations.

The first project of this thesis shows a new diborylation reaction with bis(catecholato)diboron (B₂cat₂) and [1.1.1]propellane (Paper I). The resulting product of the strain release of propellane, is demonstrated to be a methylenecyclobutane gem-diborylated molecule, fully characterized upon transesterification in situ, and reaction mechanism is proven via both kinetic studies and DFT calculations. This method offers a methodology for the synthesis of a new cyclobutane building block with potential pharmaceutical applications.

The second project describes a selective N-alkylation reaction of aniline with 1,4-diols in the presence of an amino-functionalized NHC-Ir catalyst (Paper II). The base-free conditions allow the synthesis of a wide library of δ-amino alcohols via borrowing hydrogen methodology (BHM). Application of the new method to the late-stage functionalization (LSF) of marketed drugs demonstrates the utility of the method in the field of medicinal chemistry.

The third project investigates further the remarkable reactivity of the amino-functionalized NHC-Ir catalyst in the synthesis of dialkylated indoles via BHM (Paper III). The selective functionalization of indolines under base-free conditions is achieved in a sequential process, where the N-alkylation takes place at first at lower temperature, then oxidation to indole followed by the C-alkylation is performed at higher temperature. The mechanism of the sequential dialkylation is proposed to proceed via BHM.

The last part of the thesis focuses on the use of a commercially available Ir catalyst for the reduction of nitroarenes in the presence of catalytic amounts of hydrogen peroxide (Project IV). This unexpected reactivity was investigated, and experimental results suggests a catalyst modification in situ enhancing the full reduction of nitroarenes to the corresponding anilines.