A series of 1-[1-(3,4-dimethoxy-1H-2-benzopyran-1-yl)alkyl]-4-arylpiperazines that shows hypotensive activity in the conscious rat has been investigated. Structure-activity relationships are described. A typical example that was investigated in greater detail is 1-[2-(3,4-dihydro-6,7-dimethoxy-1H-2-benzopyran-1-yl)ethyl]-4-(4-fluorophenyl)piperazine. This compound decreases sympathetic nerve activity recorded from the external carotid and splanchnic nerves of baroreceptor-denervated cats and, therefore, has a central component to its mechanism of action. It also blocks pressor effects of norepinephrine and phenylephrine and is thus an alpha-adrenergic antagonist. Binding data characterize this as alpha 1-adrenergic receptor blockade.

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Aus dem Carbonsäureester (I) erhält man die Alkohole (III)‐(V), die mit den Halogeniden (VI) oder (VII) zu den Halogenalkylisochromanen (VIII) cyclisieren.