RSK2 (p90ribosomalS6kinase2) is a serine/threonine kinase expressed in a variety of cancers. Molecular-targeted inhibition of RSK2 as a potential therapeutic strategy for human cancers has been documented. In this work, a series of isoindole-1,3-dione derivatives as novel RSK2 inhibitors were designed and synthesized from a hit discovered in our previous study. Some compounds were confirmed to