Thiazolo[5,4-f]quinazolin-9-ones, inhibitors of glycogen synthase kinase-3

In an effort to identify new protein kinase inhibitors with increased potency and selectivity, we have developed the microwave-assisted synthesis of thiazolo[5,4-f]quinazolin-9-ones. The effects of eighteen derivatives on CDK1/cyclin B, CDK5/p25, and GSK-3 were investigated. Several turned out to inhibit GSK-3 in the micromolar range. Molecular modeling studies suggest that the most selective GSK-3 inhibitors 7a–d bind into the ATP-binding site through a key hydrogen bond interaction with Val135 and target the specific hydrophobic backpocket of the enzyme.