During the three years of my PhD I was involved in the synthesis of alkyl-guanidine oligomers as perspective antibacterial agents. The research of new antibacterial drugs currently represents a cutting-adge field in medicinal chemistry, since the phenomenon of multidrug resistance (MDR) is growing very fast worldwide. MDR has been in fact defined by the World Health Organization as one of the three major threat to mankind in the 21st century, endangering the efficacy of the treatments. For this reason, both the prevention from the infections and the divulgation of awareness, as well as the help from different research area, academic and industrial, are urgently needed. My PhD thesis is divided into two main parts: the first derives from a serendipitous discovery, that trigged the beginning of the project. It was devoted to the resolution of a multicomponent mixture of oligomers, spontaneously originated, through the design and synthesis of all the possible hypothesized structures. Based on this study we have been able to identify a good candidate for next investigations, which were carried out in the second part of my work. This latter part is a more basic example of extension of a chemical class of compounds. Starting from the identified scaffold, some structural modifications have been performed in order to analyse some preliminary structure-activity relationships.