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

The new mononuclear nickel(II) complexes [Ni(H-1)(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)(2)S=O)(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 beta-nitroalcohols with good yields (67-82%) and diastereoselectivities (syn/anti 59:41-70:30). (C) 2017 Elsevier B.V. All rights reserved.