Amino Acid Salt Catalyzed Asymmetric Addition Reaction of Acetylacetone to Maleimides and 2-(2-Oxoindolin-3-ylidene)malononitriles

The exploration of catalytic potential of natural amino acid salt in activation of 1,3-dicarbonyls was carried out, in which maleimides and 2-(2-oxoindolin-3-ylidene)malononitriles were found to be good electrophiles and afforded the desired products with excellent yield and moderate optical purity. Control experiments showed that the secondary amino group of barium (S)-prolinate is critical to the catalytic activity as well as enantiocontrol, thus revealed an enamine activation mechanism is possible in the present methodology.