Syntheses and applications of enantiopure δ-amino acids and their precursors

Abstract Enantiopure unnatural homologated amino acids, whereby there is > 1 carbon atom between the C- and N- termini have found great utility in a number of applications. The enantiopure syntheses of β-amino acids are well documented, as increasingly are those of γ-amino acids. δ-Amino acids on the other hand are much less well-studied despite reports of their potential utility. This review attempts to summarise strategies that have been adopted towards the enantioselective synthesis of δ-amino acids and their precursors (e.g. nitrile/nitro/azido/ester/alcohol etc) and where appropriate demonstrate their utility. Only systems which are all carbon between the two termini are considered and only those where the shortest route between any given C -termini and any given N -termini is four carbons long ( i.e. lysine derivatives are not considered).