From a racemate to a single enantiomer: Deracemization by stereoinversion

The stereoinversion of one enantiomer into its mirror-image counterpart within a racemate furnishes a single stereoisomeric product in 100% theoretical yield. This extremely efficient type of deracemization, whereby substrate and product possess an identical chemical structure, can be achieved by using bio- or chemo-catalysts or combinations thereof and is applicable to secondary alcohols, amines and cc-substituted carboxylic acids. Special emphasis is devoted to the theoretical background of the one-pot, single-step deracernization of sec-alcohols. 1 Introduction 2 Secondary Alcohols 2.1 Single-Step Deracernization 2.2 Two-Step Deracemization 3 alpha-Aryl- and alpha-Aryloxycarboxylic Acids 4 Chiral Amines and Amino Acids 4.1 Combining an Oxidase with a Chemical Reducing Agent 4.2 Multienzyme System 5 Chemical Methods 5.1 Enantioselective Protonation 5.2 Chiral Environment 6 Conclusions