Scientists have used an enzyme to convert a racemic mixture of arylpropanals to a single enantiomer of the corresponding arylpropanols. The process could be applied to the industrial synthesis of drugs such as Ibuprofen, avoiding the 50% waste of the undesired enantiomer generated by current processes. 

Daria Giacomini and colleagues at the University of Bologna, Italy, in collaboration with Francesca Paradisi's group at University College Dublin, Ireland, used horse liver alcohol dehydrogenase enzyme for the reduction and dynamic kinetic resolution of arylpropanals to the pharmaceutically important (S)-arylpropanols. 

The (R)-propanal is less reactive in the reduction reaction than the (S)-propanal, which results in an excess of the (R)-propanal in the reaction mixture. However, because the enantiomers are in equilibrium with each other, the (R)-propanal racemises to replenish the faster reacting enantiomer, resulting in the disappearance of the unwanted enantiomer and high yields of the desired product. 

(S)-arylpropanols are intermediates in the synthesis of the Profen class of pharmaceutical products therefore Giacomini believes that her work could be applied to synthesis of these useful drugs. 'An enhanced use of purified enzymes as reagents for organic synthesis will be a real improvement towards environmentally benign chemical processes,' she commented. 

Joanne Thomson