ИСТИНА

Three new water-soluble copper (II) complexes [Cu(HL)(H2O){(CH3)2NCHO}] (1), [Cu(H2L)2(im)4]•CH3OH (2) and [Cu(HL)(CH3OH)]2(μ2-py) (3) were synthesized from copper (II) nitrate and sodium (Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzenesulfonate (NaH2L), in the absence (for 1) and presence of imidazole (for 2) or pyrazine (for 3), and fully characterized. The complexes 1−3 have been tested as stereoselective C−H activating catalysts for the model nitroaldol (Henry) condensation of nitroethane with various aldehydes in water. 1 was the most active catalyst affording 64−87% yields with syn/anti diasteroselectivities up to 77:23. A series of combinations of nitroethane and benzaldehyde, the representative model substrates, were studied in order to evaluate the catalytic efficiency of 1−3 in different solvents (Table 1). For comparative purposes, blank reactions in the absence of 1−3 were also performed in the above mentioned solvents, solvent-free conditions and in the presence of Cu(NO3)2•2.5H2O, and in all the blank experiments no β-nitroalkanol was detected.