N-Heterocyclic Carbene-Catalyzed Mukaiyama Aldol Reactions

Abstract

N-Heterocyclic carbenes were shown to be highly effective catalysts to promote Mukaiyama aldol reactions. In the presence of only 0.5 mol % of N-heterocyclic carbene (5), various aldehydes and 2,2,2-trifluoroacetophenone underwent Mukaiyama aldol reactions in THF with trimethylsilyl ketene acetal (2) at 23 °C as well as with trimethylsilyl enol ether (7) at 0 °C to afford aldol adducts in good yields. These conditions are extremely mild and operationally simple and tolerate various functional groups.