Synthesis and reactivity of some pyridyl isoxazol-5-ones

New pyridyl-5-one derivatives were synthesized by reactions of 3-(pyridin-3-yl)isoxazol-5(4H)-one (I) with various aryl aldehydes to yield 4-(arylidene-3-(pyridin-3-yl)isoxazole-5(4H)-ones (IIa-c). The reactions of these compounds with hydrazine hydrate gave new heterocyclic compounds (IIIa,b). Compound (I) reacted with phosphorus oxychloride to produce 3-(5-chloroisoxazol-3-yl) pyridine (IV). The reaction of compound (IV) with sodium azide yielded 37(57, azidoisoxazol-3-yl) pyridine (V), which was reduced with H2S to yield 3-(pyridine-3-yl)-N [3- pyridine-3-yl) isoxazol-5(4H)-ylidene] isoxazol-5-amine (VI). Different products (VII-IX) were obtained by the Vilsmeier-Haack reaction with compound (I). The reduction of 4-nitroso-3-(pyridin-3-yl) isoxazol-5(4H)-one. (X) produced compound X)Compound (XI) reacted with different reagents to produce thiourea (XII), phenylthiourea (XIII), and aminoacetic acid., (XIV) isoxazole derivatives, besides new compounds with heterocyclic rings fused to isoxazoline moiety (XV-XVII).