This thesis concerns the design and synthesis of compounds relevant to a new strategy for the synthesis of anti-cancer prodrugs. The focus of this strategy is Diels-Alder chemistry leading to oxygen or sulfur-bridged polycyclic adducts. Bridge cleavage of such adducts can result in the formation of polycyclic, aromatic compounds, a structure characteristic of anti-cancer drugs which act via intercalation. Part A describes the design of a model system for the synthesis of Diels-Alder adducts as prodrugs. A range of isobenzofurans, along with a range of fumaramide and N-aryl maleimide derivatives, were synthesised, and these were reacted together in Diels-Alder fashion. The resulting adducts were bridge cleaved. Part B describes the introduction of functional groups into Diels-Alder adducts. The functional groups investigated included alkylating and hydrogen-bonding substituents, introduced via N-aryl maleimide based dienophiles. A range of isobenzothiophenes was also synthesised, and these were used to generate sulphur-bridged Diels-Alder adducts, with the resulting increase in stability proving advantageous in some instances. A variety of functionalised adducts and their bridge cleaved derivatives were prepared. The biological properties of some showed promise as leads for the development of anti-cancer compounds.