Dynamic thermodynamic resolution of N-methylpseudoephedrine α-bromo esters for asymmetric syntheses of α-hydroxy carboxylic acid derivatives

An example of dynamic thermodynamic resolution in the nucleophilic substitution reactions of α-bromo esters with an oxygen nucleophile is described. Temperature controlled epimerization–substitution sequence provides a practical protocol for the preparation of highly enantioenriched α-hydroxy carboxylic acid derivatives up to 72% yield with 99:1 er.