Base-Promoted Transfer Hydrogenation of Difluoroalkenes with Hantzsch Ester.

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.