Synthesis of optically pure halogenated phenyl 2-hydroxypropanones by lipase-catalyzed enantioselective transesterification

Lipase-catalyzed enantioselective transesterification has been performed to obtain chiral halogenated phenyl 2-hydroxypropanones, key intermediates of pharmaceuticals. Effects of organic solvents, reaction temperature, and substrate concentration were also investigated in Novozym 435-catalyzed transesterification of 1-(2,4-difluorophenyl)-2-hydroxypropanone with vinyl butanoate. Optically pure halogenated phenyl 2-hydroxypropanones and their esters have been successfully prepared in good yields (>40%) and excellent enantiopurities (>99%) by Novozym 435-catalyzed transesterification at 30 °C in hexane.