Abstract: A process for preparing b-b dimers having anti-UV and antioxidant properties, from p-hydroxycinnamic esters and amides disubstituted in the ortho position with respect to the phenol function and from ketones disubstituted in the ortho position with respect to the phenol, in particular, from sinapic acid esters and amides and ketone analogs. The dimers of formulae (I), (II), (III) and (IV) as obtained by means of the process according to the present disclosure can be used for the production of polymers/plastics (in plastics technology), or for the protection of plants against the cold and as cosmetic or food-processing ingredients, for example. The process may be used to form biobased anti-UV molecules.