Chemoenzymatic preparation of atrolactic and Mosher's acid using Aspergillus oryzae protease

Sterically demanding α-methyl- and α-trifluoromethyl-mandelic esters 5a and 6a were conveniently resolved on a large scale by a protease from Aspergillus oryzae leading to both enantiomers of atrolactic acid 5b and a precursor of Mosher's acid 6b in 75–88% e.e. Single recrystallisation led to optically pure material.