4-(5-Isothiocyanato-1,2,3,4-tetrahydro-1-naphthyl)-1H-imidazole: An imidazole-type affinity label for the alpha(1)-adrenergic receptor

Based on the conformationally restricted analog 5 of medetomidine (4), a pr ototypic compound of the novel imidazole class of alpha (2)-adrenergic rece ptor (AR) agonists, compound 6 was prepared and evaluated at human platelet alpha (2)-AR and rat aorta alpha (1)-AR, Functional studies indicated that compound 6 behaves as an irreversible antagonist (affinity label) at alpha (1)-AR, but a reversible antagonist at alpha (2)-AR, Compound 6 may serve as a lead for developing new generation and possibly subtype-selective alph a (1)-AR affinity labels.