and at high doses it also exhibits postsynaptic antagonism.(R)-1 is a postsynaptic agonist. In a continuation of studies of effects of the p-dimethoxy moiety at dopamine receptors, synthesis and resolution of the 2, 5-dimethoxy analog 3 of 3-PPP was undertaken. The two enantiomers and the racemic modification showed cardiovascular effects consistent with actions at DA-2 receptors. The potency of all three compounds was much lower than that ...