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

Abstract

An efficient cobalt-catalyzed chemoselective reduction of β-CF3 -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-CF3 saturated ketones in one-pot. This methodology was also applied to the selective C=C reduction of other enone substrates bearing no β-CF3 -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.