Synthesis and vasorelaxant activity of 4-(cyclic amido)-2H-naphtho[1,2-b]pyrans.

A series of 4-(cyclic amido)-2H-naphtho[1,2-b]pyrans related to cromakalim (1) has been prepared and their vasorelaxant activities on isolated rat thoracic aorta precontracted with phenylephrine have been evaluated. The relaxant mechanism of 3a was found not through ATP-sensitive K(+) channels as cromakalim, but through opening voltage-sensitive K(+) channels.