Benzylamine as Hydrogen Transfer Agent: Cobalt‐Catalyzed Chemoselective C=C Bond Reduction of β‐Trifluoromethylated α,β‐Unsaturated Ketones via 1,5‐Hydrogen Transfer

An efficient cobalt‐catalyzed chemoselective reduction of β‐CF 3 ‐α,β‐unsaturated ketones using benzylamine as hydrogen transfer agent involving intramolecular 1,5‐hydrogen transfer is reported. The reaction proceeded smoothly with a relatively wide range of substrates including those bearing aromatic heterocycles such as a furyl ring system in high yields (74–92 %). This provides an efficient method for the synthesis of β‐CF 3 saturated ketones in one‐pot. This methodology was also applied to the selective C=C reduction of other enone substrates bearing no β‐CF 3 ‐substituent, of which β‐substituted or β,β‐disubstituted enones are tolerated, giving the desired products in good yields (72–75 %). Mechanistic studies indicate that the reaction involves 1,5‐hydrogen transfer.