Kinetic resolution of the racemic 2-hydroxyalkanoates using the enantioselective mixed-anhydride method with pivalic anhydride and a chiral acyl-transfer catalyst

Chemistry. 2010 Jan 4;16(1):167-72. doi: 10.1002/chem.200902257.

Abstract

A variety of optically active 2-hydroxyalkanoates and the corresponding 2-acyloxyalkanoates are produced by the kinetic resolution of racemic 2-hydroxyalkanoates by using achiral 2,2-diarylacetic acid with hindered carboxylic anhydrides as the coupling reagents. The combined use of diphenylacetic acid, pivalic anhydride, and (+)-(R)-benzotetramisole ((R)-BTM) effectively produces (S)-2-hydroxyalkanoates and (R)-2-acyloxyalkanoates from the racemic 2-hydroxyalkanoates (s-values=47-202). This protocol directly provides the desired chiral 2-hydroxyalkanoate derivatives from achiral diarylacetic acid and racemic secondary alcohols that do not include the sec-phenethyl alcohol moiety by using the transacylation process to generate the mixed anhydrides from the acid components with bulky carboxylic anhydrides under the influence of the chiral acyl-transfer catalyst. The transition state that provides the desired (R)-2-acyloxyalkanoate from (R)-2-hydroxyalkanoate included in the racemic mixture is disclosed by DFT calculations, and the structural features of the transition form are also discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkanes / chemistry*
  • Anhydrides / chemistry*
  • Catalysis
  • Kinetics
  • Molecular Structure
  • Pentanoic Acids / chemistry*
  • Stereoisomerism

Substances

  • Alkanes
  • Anhydrides
  • Pentanoic Acids
  • pivalic anhydride