A series of 4-amino-6, 7-dimethoxy-2-[4-(substituted oxyethoxy) piperidino] quinazoline derivatives (2) was synthesized and evaluated for a-adrenoceptor affinity and antihypertensive activity. Most compounds showed binding affinities within the nanomolar range for a,-receptors, although 25 and 26 showed enhanced potency (Ki, ca. 1.5 XM), equivalent to that of prazosin. Series 2 also displaced [3H] clonidine from a2- ...