RuCl3/ PPh3 ‐ Catalyzed Direct Conversion of Isoxazol‐5‐ones to 2,3‐Disubstituted Pyridines

A novel catalytic system employing RuCl3/ PPh3 is described for the preparation of 2,3‐disubstituted pyridines starting from 3,4‐disubstituted isoxazol‐5‐ones and acrolein. Mechanistic studies involving 31P NMR, HRMS analyses and control experiments have been performed in order to support key events and intermediates proposed for this transformation. 2,3‐Disubstituted pyridines can be prepared in a straightforward fashion starting from 3,4‐disubstituted isoxazol‐5‐ones and acrolein, in the presence of an unprecedented catalytic system composed of RuCl3 and PPh3. Mechanistic studies are provided in order to support key events and intermediates.