Key points are not available for this paper at this time.
The highly diastereoselective oxy-Michael addition of the "naked" anion of (6S)-methyl delta-lactol to gamma-substituted beta,gamma-unsaturated alpha-keto esters leading to the direct formation of THP*-protected gamma-hydroxy alpha-keto ester derivatives is described. Subsequent acid-mediated deprotection affords the 3-hydroxybutenolides in high yields.
Xiong et al. (Wed,) studied this question.