Synthesis of Unnatural Amino Acids: Expansion of the Chiral Pool

Although nature has been the primary source of chiral materials through extraction processes, which may also include a bioprocess, modern asymmetric synthetic methodology is now in the position to provide cheap, pure, chiral materials at scale. Thus, the chiral pool can be expanded by synthesis of the stereogenic center. Rather than duplicate sections of this book, we have chosen to discuss the problems associated with the synthesis of unnatural amino acids at various scales. This illustrates that a single, cheap method need not fulfill all of the criteria to provide a chiral pool material to a potential customer-a number of approaches are required (see also Chapter 2).