[Absolute configuration and enantiomeric purity of celiprolol]

The absolute configuration of (+)-celiprolol ([alpha]D = +6.3 degrees in CHCl3) was established by a 9-step synthesis via the (+) (R)-acetonide of (R)-glyceraldehyde. This result was confirmed by the Cupra-A CD-spectra of the isopropyl and hydroxy analogs. The enantiomeric purity was determined by NMR analysis of the diastereomeric amide esters obtained by reaction of celiprolol with 2 mol of alpha-methoxy-alpha-trifluoromethyl-phenylacetic acid chloride (Mosher's reagent).