Synthesis and α1-adrenoceptor antagonist activity of tamsulosin analogues

Tamsulosin (−)-1 is the most utilized α1-adrenoceptor antagonist in the benign prostatic hyperplasia therapy owing to its uroselective antagonism and capability in relieving both obstructive and irritative lower urinary tract symptoms. Here we report the synthesis and pharmacological study of the homochiral (−)-1 analogues (−)-2–(−)-5, bearing definite modifications in the 2-substituted phenoxyethylamino group in order to evaluate their influence on the affinity profile for α1-adrenoceptor subtypes. The benzyl analogue (−)-3, displaying a preferential antagonist profile for α1A-than α1D-and α1B-adrenoceptors, and a 12-fold higher potency at α1A-adrenoceptors with respect to the α1B subtype, may have improved uroselectivity compared to (−)-1.

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