ИСТИНА

Herein we report the synthesis and characterization of chiral copper(II) CPs based on Schiff bases of (S)-2-aminomethylpyrrolidine and salicylaldehyde derivatives including both Lewis and Brønsted acid/basic functions (Figure). In addition, their application as catalysts in enantioselective Henry reaction was detailed (Figure). It was demonstrated that the water molecules play a crucial role in the reactivity of CPs in the enantioselective Henry reaction with up to 82% ee. The mechanism of the reaction was kinetically studied and shown to involve two Cu-complexes, acting in concert with both Cu-ions and NH-centers activating the substrates. The bridging OAc-ion functioned as the basic group, deprotonating nitromethane molecules. The step was found to be the rate-limiting in the reaction with the observed kinetic isotope effect equal (KIE) 6.4.4 We have showed that, at least, some copper(II) complexes derived from tridentate complexes become real catalysts only in the presence of water in solution. Their activity may vary within several orders of magnitude and water presence may become a crucial feature of the catalysis by copper(II) complexes.