Iron-Catalyzed Transfer Hydrogenation in Aged <i>N</i>‑Methyl-2-pyrrolidone: Reductive Ring-Opening of 3,5-Disubstituted Isoxazoles and Isoxazolines

3,5-Disubstituted isoxazoles and isoxazolines undergo an iron-catalyzed reductive ring-opening in aged <i>N</i>-methyl-2-pyrrolidone (NMP). 5-Hydroxy-<i>N</i>-methyl-2-pyrrolidone generated <i>in situ</i> via a simple activation of commercial NMP acts as the hydrogen donor in the iron-catalyzed transfer hydrogenation reaction. It is the first example employing a combination of an iron catalyst and 5-hydroxy-<i>N</i>-methyl-2-pyrrolidone as reducing agents in a transfer hydrogenation reaction. The protocol is highly efficient for the synthesis of β-enaminones and 1,3-diketones, providing a versatile route for the preparation of these 1,3-difunctional compounds bearing diversified substitution patterns.