Recent Developments in the Synthesis of Fluorinated β-Amino Acids

Synthetic studies on fluorinated β-amino acids and β-peptides have expanded rapidly in recent years, and particularly significant are those methods giving access to the target compounds in enantiomerically pure form. Two main strategies have been investigated, namely selective fluorination of appropriate functional groups in β-amino acid frameworks, and exploitation of already fluorinated small molecules for their use as synthetic building blocks. In addition, fluorine-containing β-lactams have often been employed as synthetic intermediates for the preparation of the corresponding β-amino acids. A large variety of acyclic β-amino acids has been reported, containing one or two fluorine atoms at the α-position, as well as α- or β-fluoroalkyl substituents. In contrast, fluorinated cyclic derivatives are much more unusual. Furthermore, the first examples of peptidic molecules containing fluorinated β-amino acids in combination with non fluorinated α- or β-amino acids have recently appeared. These compounds have been studied in terms of structure, proteolytic stability and biological activity.