ECD spectrometric methods for detecting the enantioselective enzymatic hydrolysis of racemic 3-acetoxy-4-phenyl-β-lactam

(−)-(3R, 4S)-3-Acetoxy-4-phenylazetidin-2-one ((−)-1) was the key intermediate for preparing optical C-13 side-chain moiety in partial synthesis of docetaxel and paclitaxel. It can be successfully prepared via enantioselective hydrolysis of racemic esters ((±)-1) catalyzed by bacterial lipases, but the current reaction evaluation method is tedious and inconvenient. Electronic circular dichroism (ECD) has been widely applied in the stereochemical study of chiral compounds. In this paper, a rapid ECD spectroscopic method has been proposed and established to detect the transformation directly. The absolute configurations of lipase-catalyzed hydrolysis products have also been confirmed by quantum-chemical calculation using time-dependent density functional theory (TDDFT) methodology.