A Flash Thermal Racemization Protocol for the Chemoenzymatic Dynamic Kinetic Resolution and Stereoinversion of Chiral Amines

A highly practical and effective ‘Flash Thermal Racemization’ (FTR) protocol was developed in continuous flow, without needing a base or a H donor. This can be integrated with an enzyme to enable the chemoenzymatic kinetic resolution of primary amines to be achieved in a more atom-efficient manner without additives. An unprecedented space-time yield of up to 1362 μmol mL–1 h–1 can be achieved for the dynamic kinetic resolution of 1-aminoindane, which is at least 10 times more productive than previously reported, and up to 1700-fold more productive when the Pd catalyst loading is taken into account. With a slight modification, the flow reactor system can also be used to convert an optically active amine to its opposite enantiomer.