The first synthesis of isoxazolo[3,4-c]pyridine-7-ones

Abstract During the lead-oriented synthesis of new heterocycles, ethyl 4-(cyanomethyl)-5-phenylisoxazole-3-carboxylate was identified as a key intermediate towards the synthesis of new isoxazolo[3,4- c ]pyridine scaffolds. The key reaction was the catalytic hydrogenation of ethyl 4-(cyanomethyl)-5-phenylisoxazole-3-carboxylate using Raney/Ni followed by a selective ring closure reaction to afford 3-phenylisoxazolo[3,4- c ]pyridin-7(6 H )-one and its unsaturated analogue as new ring systems with lead-like properties.