High Pressure in Organocatalysis

Significance

Kwiatkowski and co-workers disclose an enantioselective Michael addition of nitromethane to β,β-disubstituted enones by applying a high-pressure methodology. By using cinchonine-based primary amine catalyst 1, benzoic acid as a co-catalyst, and applying 10 kbar of hydrostatic pressure, good yields and good to excellent enantioselectivities could be obtained for both cyclic and acyclic β,β-disubstituted enones. With nitroethane as nucleophile the reaction proceeded to give high yield and enantioselectivity but poor diastereoselectivity (dr ˜ 1:1). A survey of different pressures showed that reducing the pressure had no effect on the enantioselectivity, but proved to be severely detrimental to conversion as well as isolated yield (comparable results were obtained at pressures of 4 kbar or above).