We have focused on four projects during my PhD studies. In chapter 2, we describe a mild and use-friendly Ni-catalyzed cascade cyclization/carboxylation using CO2 in which the selectivity pattern is dictated by substrate and/or ligand selection. In chapter 3, we describe a Ni-catalyzed hydrocarboxylation of alkynes that occurred with a C2 regioselectivity profile using commercially available alcohols as proton source. In chapter 4, we describe a convenient Ni-catalyzed hydroamidation protocol of alkynes with isocyanates that utilizes simple alkyl bromides as hydride sources. Unlike the hydrocarboxylation protocol, this transformation occurred with excellent C1-selectivity. And in chapter 5, we describe an aryl iodide catalyzed C(sp2)-H and C(sp3)-H functionalization/C-O bond formation reaction. The reactions occurred under mild conditions and with an intriguing selectivity switch depending on the catalyst used.