Used as a chiral auxiliary in asymmetric synthesis, this acetic acid ester derivative enables highly stereoselective double aldol reactions. It facilitates the formation of complex polyol structures with excellent diastereo- and enantiocontrol, making it valuable in the synthesis of natural products and bioactive molecules. The reagent’s bulky mesitylenesulfonyl and benzyl groups help direct stereochemical outcomes by shielding one face of the enolate intermediate. After the desired transformation, the auxiliary can be cleaved under mild conditions, leaving the chiral framework intact. Its application is particularly useful in pharmaceutical research where precise stereochemistry is critical.