Base catalyzed racemization of amino acid derivatives

Amino acid thioesters used as substrates for a chemo-enzymatic dynamic kinetic resolution (DKR) must be designed with a high enough acidity to be rapidly racemized in the presence of a suitable base. Kinetic data obtained from experimental proton exchange rates are correlated with thermodynamic data for the proton abstraction based on the density functional theory (DFT) calculations. The good correlation obtained allows to evaluate the contribution of different functional groups to the carbon acidity and to define bases able to perform the required racemization. (C) 2011 Elsevier Ltd. All rights reserved,