Asymmetric Synthesis of (R)- and (S)-Moprolol

A simple and effective procedure for the enantioselective synthesis of (R)- and (S)-Moprolol was described. The key step was the asymmetric synthesis of enantiopure (R)- and (S)-guaifenesin, which were synthesized from enantioenriched (R)-3-chloro-1,2-propanediol and (S)-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^III complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ¹H NMR, ¹³C NMR, IR, and MS.