New chemo-enzymatic approaches for the synthesis of (R)- and (S)-bufuralol

Both enantiomers of bufuralol are pharmaceutically important molecules. While the (S)-isomer with a higher β-blocking activity is recommended for hypertension treatment, the (R)-enantiomer can be used as marker of hepatic activity. In this paper two new alternative approaches are described for their chemo-enzymatic synthesis, providing both highly enantiomerically enriched stereoisomers of the target molecule (ee 96-98%). One route is based on the baker's yeast mediated stereoselective biotransformation of α-substituted ketones, and the other one on the lipase mediated kinetic resolution of the racemic bromoethanol.