Synthetic Efficiency

Abstract

The efficiency of a synthesis can be described in three different ways: (1) atom economy, (2) overall yield, and (3) the E-factor or PMI. Atom economy is most useful for comparing the efficiency of different proposed synthetic routes. Overall yield is used widely in the organic literature to measure the production of product based on the limiting reagent, but yield does not include the atom economy or the use of auxiliaries. Sheldon's E-factor and the PMI are quantitative ways to describe the efficiency of a process that include atom economy, overall yield, and auxiliaries. The synthesis of single-enantiomer drugs is an important way to improve both the efficiency of production and the effectiveness of the final product. Strategies for more efficient production of drugs taking stereochemistry into consideration focus on: (1) design of achiral drugs, (2) application of asymmetric catalysts, (3) use of asymmetric biofeedstocks, (4) enzymatic resolution, (5) resolution of diastereomeric salts, and (6) resolution of diastereomeric covalent derivatives.