A structure-activity study of four dopamine D-1 and D-2 receptor antagonists, representing the phenylindan, -indene,...

Representatives of the phenylindan, -indene, and -indole classes of compounds (3-6) have been tested for affinity for the dopamine D-1 and D-2 receptors. The compounds all display high affinities for these receptors. Conformational analysis using MM2(87) and subsequent molecular least-squares superimpositions have been performed in order to determine if the affinities of the compounds can be rationalized by a recently proposed dopamine D-2 receptor-interaction model. In spite of the different geometric and conformational properties, the compounds can be well accommodated into the model in their calculated lowest energy conformations. The molecular superimpositions allow the absolute configurations of the active enantiomers of 4 and 5 to be predicted. The present structure-activity study extends the receptor-interaction model by suggesting that the receptor is not very sensitive to the orientation of the p-fluorophenyl ring in 1 and 3-6 or to the exact spatial location of the associated fluoro substituent.