Mononuclear nickel(II) complexes with arylhydrazones of acetoacetanilide and their catalytic activity in nitroaldol reaction

Abstract

The new mononuclear nickel(II) complexes [Ni(HL1)(H2O)2(CH3OH)] (1, NaH2L1=sodium (Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzenesulfonate) and [Ni(H2L2)2(H2O)4] [(CH3)2SO)2] (2, H3L2=(Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzoic acid) were synthesized and characterized by IR and ESI-MS spectroscopies, elemental and X-ray crystal structural analyses. Both compounds 1 and 2 act as homogenous catalysts for the diastereoselective nitroaldol (Henry) reaction of aliphatic and aromatic aldehydes with nitroethane in different solvents such as acetonitrile, methanol or water. Complex 1 was found to be the more efficient catalyst for the Henry reaction in aqueous medium, providing β-nitroalcohols with good yields (67–82%) and diastereoselectivities (syn/anti 59:41–70:30).