1: 72 percent / nitromethane / 48 h / Ambient temperature 2: 67 percent / lithium dicyclohexylamide / tetrahydrofuran; hexamethylphosphoric acid triamide / Ambient temperature 3: 78 percent / 2,3-dichloro-5,6-dicyanobenzoquinone / benzene / 1 h / Heating 4: 36 percent / tetrabutylammonium fluoride / tetrahydrofuran / Ambient temperature 5: 59 percent / Amberlyst A15 resin (H(1+) form) / CH2Cl2 / 10 h / Ambient temperature View Scheme