The Henry reaction catalyzed by NiII and CuII complexes bearing arylhydrazones of acetoacetanilide

Abstract

The new nickel coordination polymer [Ni(HL1) (CH3OH)2]n (1) and co-crystal H3L1∙DMF (2) were obtained by reaction of NiCl2·2H2O with 2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene) hydrazineyl)benzoic acid (H3L1) in the presence and absence of triethylamine, respectively, in a mixture of methanol and dimethylformamide (DMF) (20:1, v/v). Reaction of CuCl2·2H2O with H3L1 in the presence of 2,2'-(methylazanediyl)bis (ethan-1-ol) (HR) in methanol yields [Cu(HR)2(H2L1)2] (3), whereas treatment of this copper salt with sodium 2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazineyl)benzenesulfonate (NaH2L2) in a mixture of acetone and water (10:1, v/v) produces [Cu(HL2) (H2O)2]∙2(H2O)∙{(CH3)2C = O} (4). Compounds 1−4 were characterized by IR and ESI-MS spectroscopies, elemental and X-ray crystal structural analyses, and tested as catalyst for the Henry reaction of aliphatic and aromatic aldehydes with nitroethane in different solvents such as acetonitrile, methanol or water. Good yields (up to 87%) and diasteroselectivities (syn/anti 77:23) were observed in the reactions catalyzed by 3 in water.