This thesis describes the development of novel methods for selective oxidation and reduction reactions based on the concept of “Green Chemistry”. The work focuses on the replacement of precious metal-catalysts, e.g. ruthenium-complexes, by cheaper, more abundant and less or non-toxic iron based catalysts. In the oxidation section, protocols for the selective transformation of arenes to their corresponding quinones are reported applying hydrogen peroxide. At first, a ruthenium-based procedure was developed which is replaced in a second step by an analogue in situ generated iron-based system. When focussing on reduction reactions, well-defined iron-tetraphos catalysts were used for the transfer hydrogenation of nitroarenes, terminal alkynes and aldehydes using formic acid as reducing agent. A second iron-tetraphos generation utilizes molecular hydrogen for the selective reduction of nitroarenes or aldehydes. Furthermore, homogeneous molybdenum-catalysts as well as heterogeneous iron- and cobalt-catalysts were applied for the reduction of nitroarenes.