Pyridine derivatives of the formula ##STR1## wherein the ring A stands for an optionally further substituted benzene ring; the ring B stands for an optionally substituted pyridine ring; Q stands for hydroxyl group, or OQ.sup.1 or Q.sup.1 wherein Q.sup.1 stands for an optionally substituted aliphatic hydrocarbon group; and n denotes 0 or 1, or their salts, which have potassium.channel opening activity and are useful as therapeutic agents of circulatory diseases such as angina pectoris, hypertension, etc.
The search for novel K+ channelopeners with a non-benzopyran skeleton, unlike cromakalim, led to the discovery of a new series of (Z)-2-(alpha-alkoxyimino)benzylpryridine derivatives. Synthesis was achieved by using a (Z)-dominant condensation reaction of benzoylpyridines with O-alkylhydroxylamines, followed by m-chloroperbenzoic acid (m-CPBA) oxidation. The compounds were tested for their vasorelaxant