Enantioselective epoxidation of chalcone catalysed by the artificial enzyme poly-L-leucine: kinetic mechanism

An insight into the kinetics, mechanism and optimum reaction conditions of the Julia-Colonna enantio selective epoxidation has been gained using a soluble polyleucine catalyst (PLL), chalcone as the substrate, and hydrogen peroxide (HOO-) as the oxidant. PLL shows saturation kinetics for both chalcone and HOO- and has a behaviour that fits a steady state random bireactant system with one of the pathways (HOO- binding first) being kinetically preferred to the other (chalcone binding first) in the formation of the ternary complex PLL:HOO-:Chalcone. (C) 2004 Elsevier Ltd. All rights reserved.