A convenient method for the kinetic resolution of racemic 2-hydroxyalkanoates using diphenylacetic anhydride (DPHAA) and a chiral acyl-transfer catalyst

Abstract

Diphenylacetic anhydride (DPHAA) was found to be a useful reagent for the kinetic resolution of racemic 2-hydroxyalkanoates in the presence of a catalytic amount of ( R)-benzotetramisole (( R)-BTM). The combined use of DPHAA and ( R)-BTM effectively produced a variety of the optically active 2-hydroxyalkanoates and the corresponding 2-acyloxyalkanoates from racemic 2-hydroxyalkanoates ( s-values = 42–177). A fairly broad substrate scope was demonstrated by this novel chiral induction system. We also revealed that the use of only 0.3 equiv of DPHAA is enough to provide the optically active 2-acyloxyalkanoates in good yields and with excellent ee’s by the added use of 0.3 equiv of pivalic anhydride for the kinetic resolution of the racemic 2-hydroxyalkanoates.