The first part of this study deals with the parametrization of these fragments. The mapping and non-bonded interactions are then set according to the guidelines for parametrizing new molecules for the Martini 3 force field . The parameters for bonded interactions are determined via Swarm-CG , using trajectories of isolated fragments in water in their atomistic representation as input. Transfer free energies, calculated using the COSMO-RS method are used as references, to be compared with free energy values, calculated with the coarsegrained fragments.