A series of 1-phenyl-, 4-phenyl-, and 1-benzyl-1, 2, 3, 4-tetrahydroisoquinolines have been prepared as ring-contracted analogues of the prototypical D, dopamine receptor antagonist SCH23390 [(R)-(+)-7-chloro-8-hydroxy-3-methyll-pheny1-2, 3, 4, 5-tetrahydro-lH-3- benzazepine]. The affinity and selectivity of these isoquinolines for D1 receptors was determined by three biochemical endpoints in membrane homogenate5 prepared from rat ...