Synthesis of novel benzo-fused heteroaryl derivatives as Ca ²⁺/calmodulin-dependent protein kinase II inhibitors

Based on the structure activity relationship of 2-(4-phenoxybenzoyl)-5- hydroxyindole (1), a novel structural class of Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII) inhibitors were synthesized. We show in this study that the acidic proton at the N(1)-position of the indole moiety is not essential for CaMKII inhibitory activity. Among the synthesized compounds, we found the benzofuran and benzothiazole derivative as promising scaffolds for the developement of potent CaMKII inhibitors. In particular, compounds 8 and 14 inhibited CaMKII with IC₅₀ values of 24 nM and 32 nM, respectively.