Nowadays, the facile modification of biomolecules under near physiological conditions is a focal point of interest in chemical biology, e.g. to track these molecules in living systems, to improve the stability of therapeutic proteins and to map protein-protein interactions, etc. Consequently, the demand of specifically designed small-molecular probes able to react specifically with the biomolecule of interest has become of increasing importance in recent years. To speed up the development of suitable reagents being able to selectively modify certain amino acid residues of proteins, in the present thesis, the synthesis of these chemical probes was accomplished by multicomponent reactions. Furthermore, besides the applicability of the Sakai reaction as new bioconjugation method, the potential of specifically designed multifunctional chemical probes to enrich enzymes with a common function was investigated.