The invention relates to the novel substituted 3-arylsulfonyl-pyrazolo[1,5-a]pyrimidines of the general formula 1, pharmaceutically acceptable salts and/or hydrates thereof, serotonin 5-HT6 receptor antagonists and pharmaceutical compositions, and also to method for prophylaxis and treatment of various diseases of central nervous system at humans and warm-blooded animals pathogenesis of which is associated with serotonin 5-HT6 receptors, in particular, Alzheimers disease, Parkinsons disease, Huntingtons disease, schizophrenia, and other neurodegenerative diseases, cognitive disorders and obesity.In the general formula 1:wherein: X=S, SO or NH R1 represents hydrogen, optionally substituted C1-C3alkyl, cycloalkyl, adamantyl, aryl or heterocyclyl R2 represents hydrogen, halogen, optionally substituted C1-C3alkyl, substituted hydroxyl, aryldiazenyl or optionally substituted amino group R3 represents hydrogen, optionally substituted C1-C3alkyl, substituted hydroxyl, pyridyl or optionally substituted amino group, besides, in cases when X=S or X=NH, at least one of R1, R2 or R3 represent substituted C1-C3alkyl, cycloalkyl, adamantyl, aryl, heterocyclyl, halogen, substituted hydroxyl, optionally substituted amino group, aryldiazenyl, or at least two of R1, R2 or R3 represent hydrogen R4 represents C1-C3alkyl R5 represents hydrogen, one or two halogens, C1-C3alkyl or optionally substituted hydroxyl.
