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Published on: June 21, 2017
Base-Promoted Transfer Hydrogenation of Difluoroalkenes with Hantzsch Ester
Yunhan Zhang1, Xinyun Qi1, Miaomiao Tian1
1State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, Henan Normal University, Xinxiang, Henan 453007, China.
None:
A metal-free transfer hydrogenation of nonactivated difluoroalkenes using Hantzsch ester as the hydrogen donor and sodium tert-butoxide as the base is reported. This method provides efficient access to a variety of difluoromethylated compounds under mild conditions without the need for transition metal catalysts or molecular hydrogen. The reaction exhibits a broad substrate scope, tolerating electron-donating and -withdrawing groups, as well as heterocyclic, nitro, and cyano functionalities. Mechanistic studies suggest that the reaction proceeds via base-mediated enolization and olefin migration to form a conjugated intermediate, followed by hydride transfer from the Hantzsch ester. Gram-scale synthesis and diverse product derivatization highlight the practical utility of this approach.
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