Phenylalkylamines such as 1-(4-bromo-2, 5-dimethoxyphenyl)-2-aminopropane (DOB; 1a) and its corresponding iodo derivative DOI (2) are commonly used 5-HT2 serotonin agonists. Previous studies have established that the 2, 5-dimethoxy substitution pattern found in these compounds is optimal for high affinity at 5-HT2A receptors and that substituents at the 4- position can modulate affinity over a wide range. We have previously shown, however, ...