The present invention relates to novel substituted 2-amino-3-(arylsulfonyl)pyrazolo[1,5-a]pyrimidines of general formula 1, to serotonin 5-HT6 receptor antagonists, to novel drug substances and pharmaceutical compositions, to medicaments, methods for preparation thereof, and to methods for prophylaxis and treatment of various CNS diseases, pathogenesis of which is associated with disturbance of monoaminergic signaling pathways, more specifically over- or hypo-activation of serotonin 5-HT6 receptors.In general formula 1Ar represents optionally substituted aryl or optionally substituted heterocyclyl R1 and R3 independently of each other represent C1-C3 alkyl or aryl R2 represents hydrogen or C1-C3 alkyl R41, and R42 independently of each other represent hydrogen, optionally substituted C1-C3 alkyl or optionally substituted phenyl, or R41 and R42 together with nitrogen atom they are attached to form optionally substituted heterocyclyl.
