Rauhut-Currier type homo- and heterocouplings involving nitroalkenes and nitrodienes

Reaction of nitroalkenes or nitrodienes with methyl vinyl ketone (MVK) or acrylate in the presence of the imidazole-LiCl catalyst system provides Rauhut-Currier (vinylogous Morita-Baylis-Hillman) adducts in moderate yield. Under similar conditions (imidazole-hydroquinone), nitroalkenes and nitrodienes undergo self-dimerization to afford the Rauhut-Currier adducts in varying yields. An alternative self-dimerization-nitro group elimination pathway in the presence tricyclohexylphosphine was observed with heteroaromatic nitroalkenes. A synthetically useful one-pot two step transformation of Rauhut-Currier adducts of nitroalkenes with MVK to 2,3-disubstituted cyclopentenones is also described.