Metal Ion-Catalyzed Hydrolysis of Acrylate Esters and Amides by Way of Their Conjugate Addition Adducts

Article abstract of DOI:10.1021/jo00127a032

A formal catalytic cycle for the metal ion-catalyzed hydrolyses of acrylamide and acrylate esters is described.While various transition metal ions show little accelaration of hydrolysis reactions in free water, bringing them into proximity with esters and amides can yield increased hydrolysis rates.Such proximity effects can be brought about by covalent addition of donor atoms near the functional group.However, the simple canjugate adducts of butylmethylamine to methyl acrylate and to acrylamide did not demonstrate metal ion-catalyzed hydrolysis.Conjugate addition of a chelating amine, N-benzyl-N',N'-dimethylethylenediamine, yields adducts demonstrating significant (up to 1.5E4-fold) hydrolysis catalysis by Cu(II) at pH 7.5 and room temperature.A model compound to test for improvement of this effect by conformational locking demonstarted no rate increase.A model compound designed to test for enhanced acceleration by two adjacent metal ions similarly showed no rate advantage as compared to the parent conjugate adduct.The conjugate reversion reaction of 3-((2-(dimethylamino)ethyl)benzylamino)propionic acid demonstrated a bell-shaped pH-rate profile with maximum rate at pH 3.