Cu-Catalyzed C(sp−H)-Trifluoromethylation of Aldehyde Hydrazones with Langlois Reagent

The C(sp−H)-trifluoromethylation of hydrazones would give access to the α-trifluoromethylated hydrazones that can serve as intermediates in the synthesis of pharmaceutically interesting fluorinated compounds. Herein, we demonstrate the Cu-catalyzed C(sp−H)-trifluoromethylation of the aldehyde hydrazones using the readily available and cost effective Langlois reagent (sodium trifluoromethanesulfinate). This reaction is broadly applicable to a series of aromatic aldehyde N-aminomorpholine hydrazones to give the corresponding C(sp)-trifluoromethyl hydrazones in moderate to high yields. The reaction generally tolerates a series of electron-releasing as well as electron-withdrawing substituents on the aromatic ring.