Copper-Catalyzed Dehydrogenative Cross-Coupling Reaction Between Allylic C—H Bonds and α-C—H Bonds of Ketones or Aldehydes.

A dehydrogenative cross-coupling reaction between allylic C-H bonds and the α-C-H bond of ketones or aldehydes was developed using Cu(OTf)2 as a catalyst and DDQ as an oxidant. This synthetic approach to γ,δ-unsaturated ketones and aldehydes has the advantages of broad scope for both ketones and aldehydes as reactants, mild reaction conditions, good yields and atom economy. A plausible mechanism using Cu(OTf)2 as a Lewis acid catalyst was also proposed (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone; Tf=trifluoromethanesulfonate).