Developing new strategies and methods to explore new dimensions of the chemical space represents an important goal for organic chemists. One particular synthetic approach that emerged in the last decades is Umpolung: the normal polarity of chemical functional groups is reversed in order to access new disconnections. The combination of non-classical ways to disconnect bonds and asymmetric methods is especially highly desirable when considering that chirality is essential to the function of many small molecules in biological systems. Among all functional groups present in organic molecules, carbonyl compounds occupy a central position due to their versatile reactivity and constitute therefore a prime target for the development of new asymmetric methods based on the Umpolung of the reactivity. In this thesis, I present my contribution to the development of novel ï ¡-functionalizations of carbonyl compounds based on the Umpolung of alkynes and azides. The products obtained, namely α-alkynyl and α-azido carbonyl compounds, represent important structural motifs of bioactive molecules and materials. They are also versatile building blocks that undergo a plethora of transformations based on the exceptional reactivity of azides and alkynes. Nevertheless, there are only few methods in literature to prepare them in a selective and efficient way.