This invention relates to novel substituted isoindoline-1,3-dione derivatives and pharmaceutically acceptable salts thereof. More specifically, the invention relates to novel substituted isoindoline-1,3-dione derivatives that are analogues of apremilast. This invention also provides compositions comprising a compound of this invention and a carrier and the use of disclosed compounds and compositions in methods of treating diseases and conditions that are beneficially treated by administering apremilast.