Applications of biotransformations and biocatalysis to complexity generation in organic synthesis.

This tutorial review provides a survey of syntheses in which an enzymatic step contributed to generating downstream molecular complexity in the target. The first part provides a guide to the types of enzymatic transformations suitable for incorporation into synthetic schemes. The principles of symmetry, especially the concept of "latent symmetry", which are often used to simplify enantiodivergent design of targets, are discussed next. The examples are discussed in the order of a degree of experimental difficulty associated with the execution of a particular biological technique. Lipase resolutions and desymmetrizations are discussed first followed by more advanced protocols involving oxidoreductase enzymes and ending with examples of syntheses that employ pathway engineering and directed evolution of proteins. Future prospects of biocatalytic methods as means of efficient preparation of target compounds are indicated. The authors hope that the review will serve to convince those synthetic chemists reluctant to use biological methods to include enzymatic procedures in their design.