Fast DKR of amines using isopropyl 2-methoxyacetate as acyl donor

The dynamic kinetic resolution (DKR) of various primary amine substrates was performed using a modified version of the Backvall system. A single equivalent of isopropyl 2-methoxyacetate was used as acyl donor in combination with p-MeO Shvo complex as the racemization catalyst and Novozym 435 as the acylation catalyst. A reaction temperature of 100 °C was employed to ensure a high racemization rate. Adding 2,4-dimethyl-3-pentanol (DMP) as hydrogen donor at a concentration of 0.5 M successfully suppressed side product formation. Under these modified DKR conditions, complete conversion was observed for most substrates within 26 h showing both high ee values and good chemoselectivity, whereas the original system required a reaction time of 72 h.