Synthesis and structure-activity relationship of 4-(1,3-benzothiazol-2-yl)-thiophene-2-sulfonamides as cyclin-dependent kinase 5 (cdk5)/p25 inhibitors

4-(1,3-Benzothiazol-2-yl)thiophene-2-sulfonamide (4a) was found to be a moderately potent inhibitor of cyclin-dependent kinase 5 (cdk5) from a HTS screen. The synthesis and SAR around this hit is described. The X-ray coordinates of ligand 4a with cdk5 are also reported, showing an unusual binding mode to the hinge region via a water molecule.