1H‐Pyrazolo‐[3,4‐c]cyclophepta[1,2‐c]thiophenes: A Unique Structural Class of Dopamine D4 Selective Ligands.

Abstract A series of novel 1 H -pyrazolo-[3,4- c ]cyclophepta[1,2- c ]thiophenes was prepared and screened at selected dopamine receptor subtypes. Compound 4 (NGB 4420) displayed high affinity and selectivity (>100-fold) for the D 4 over D 2 and other CNS receptors. This compound was identified as a D 4 antagonist via its attenuation of dopamine agonist-induced GTPγ 35 S binding at D 4 receptor.