From amino acids to heteroaromatics--thiopeptide antibiotics, nature's heterocyclic peptides

Amino acids, the building blocks of proteins, also serve as precursors to a wide range of other naturally occurring substances including alkaloids, antibiotics, and, the subject of this Review, heterocyclic peptides. Simple alpha-amino acids are converted into complex arrays of heteroaromatic rings that display interesting and potent biological activity. The thiopeptide antibiotics, with their complex molecular architectures, are wonderful examples. In this Review we show how organic chemists have developed innovative methods for the synthesis of the heterocyclic ring systems, including routes inspired by the likely biosynthetic processes, and successfully assembled such building blocks into the final target molecule by application of orthogonal protecting groups and coupling methodologies.