2,5-Bis(3,4-dimethoxybenzyl)cyclopentylamine, a peripheral dopamine blocking agent.

2,5-Bis(3,4-dimethoxybenzyl)cyclopentylamine hydrochloride has been synthesized. The intermediate 2,5-bis-(3,4-dimethoxybenzyl)cyclopentanone was formed in 91.8% yield using a sodium methoxide catalyzed aldol condensation and catalytic reduction. The oxime of this ketone was catalytically hydrogenated to the amine which was converted to the hydrochloride (76%). The amine hydrochloride was found to be an effective antagonist to the low-dose hypotensive effect of dopamine; the half-life of this effect was 18 min. At dopamine doses of 3 mg/kg in the atropinized and phenoxybenzamine treated dog, the ED50 for blockade was 4--5 mumol/kg. In direct contrast to its peripheral dopamine blocking activity, the compound potentiates apomorphine-induced stereotypy.