Pd- and Cu-Catalyzed 1,4-Addition of Dialkylzinc Compounds to α,β-Enals

Significance

1,4-Addition of organometallic reagents to conjugated double bonds is a widely used C-C bond forming reaction for the synthesis of complex organic molecules. While a large amount of work has been dedicated to the 1,4-addition to enones, addition to enals is less explored. The authors reported here a new simple protocol for a highly selective Pd-catalyzed 1,4-addition of diorganozincs to enals. Besides, the conditions for the cyanocuprate-catalyzed addition of dialkylzincs to enals were found. In the case of chiral substrates, the reactions are highly diastereoselective. Addition of TBSOTf in those cases allows the isolation of (E)-enol silyl ethers.