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

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posted on 11.12.2019 by Xiaochen Liu, Dongsub Hong, Netanel G. Sapir, Wen Yang, William H. Hersh, Pak-Hing Leung, Dingqiao Yang, Yu Chen
3,5-Disubstituted isoxazoles and isoxazolines undergo an iron-catalyzed reductive ring-opening in aged N-methyl-2-pyrrolidone (NMP). 5-Hydroxy-N-methyl-2-pyrrolidone generated in situ 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-N-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.