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.