In recognition of the need to develop novel therapeutic agents and efficient methods for the synthesis thereof, the present invention provides novel inhibitors of histone deacetylases, tubulin deacetylases, and/or aggresome inhibitors, and pharmaceutically acceptable salts and derivatives thereof. The inventive compounds fall into two classes—isotubacin class and isoisotubacin class—all of which include a 1,3-dioxane core. The present invention further provides methods for treating disorders regulated by histone deacetylase activity, tubulin deacetylase activity, and/or the aggresome (e.g., proliferative diseases, cancer, inflammatory diseases, protozoal infections, protein degradation disorders, protein deposition disorders, etc.) comprising administering a therapeutically effective amount of an inventive compound to a subject in need thereof. The present invention also provides methods for preparing compounds of the invention.