Enantioselective Organocatalyzed Michael Additions of Nitroalkanes to 4-Arylidenedihydrofuran-2,3-diones and 4-Arylidenepyrrolidine-2,3-diones

Tremendous efforts have been devoted to the development of organocatalytic enantioselective Michael additions of nitroalkanes to alpha,beta-unsaturated carbonyl compounds. However, using highly substituted electrophiles remain challenging, since the additional substituents decrease the electrophilicity. beta-Arylidene-alpha-ketolactones and alpha-ketolactams are used as highly electrophilic Michael acceptors that afford the corresponding products in moderate to good yields, with high enantioselectivities. This success relies on their rigid structure that prevents deconjugation and the efficient recognition of the alpha-dicarbonyl motif by the hydrogen-bond donor catalyst.