Chiral Auxiliaries in Drug Synthesis

The growing proportion of drugs reaching the market as single enantiomers has placed an increasing demand on the discovery of robust asymmetric methods for their synthesis. Consequently, chiral catalysis, separations, salt resolutions, and auxiliary‐controlled reactions have now largely replaced the chiral‐pool approach to synthesizing enantiomerically pure drugs. Although chiral auxiliaries may seem antiquated in light of the increasing scope of asymmetric catalysis, the chiral auxiliary approach is still optimal for a variety of key synthetic transformations and continues to play an important role in both drug discovery and development. This chapter provides a survey of chiral auxiliaries used in the synthesis of drugs, with examples chosen based on their demonstrated utility on scale.