Stereoselective construction of carbocycles and heterocycles via cascade reactions involving curcumins and nitroalkenes

The reaction of curcumins with nitroalkenes has been investigated for the first time. Highly functionalized cyclohexanones possessing three contiguous chiral centers with complete diastereoselectivity have been synthesized through an inter-intramolecular double Michael reaction involving curcumin and nitroalkene under extremely simple experimental conditions (K2CO3 in aqueous THF). Under identical conditions, curcumins react with α-bromonitroalkenes to afford dihydrofurans through an intermolecular Michael addition-intramolecular nucleophilic substitution (O-alkylation), which is analogous to an 'interrupted' Feist-Benary reaction. These novel transformations of curcumins empower us to expand the repertoire of curcumin based therapeutics.