A series of isoxazole derivatives structurally related to broxaterol 1 has
been prepared and tested for their potency to beta(1) and beta(2) adrenergi
c receptors. At variance with broxaterol, none of the tested compounds disp
layed agonistic activity. The 3-isopropenyl derivative 5f is the most poten
t antagonist both in the trachea and atria preparations.