Overview of the Synthesis of Optically Active 3-Amino-2-Hydroxy-4-Phenylbutyric Acids, Key Intermediates for Numerous Bioactive Compounds

3-Amino-2-hydroxy-4-phenylbutyric acids (AHPA or alternatively abbreviated AHPBA) serve as chiral building blocks for various bioactive compounds including aminopeptidase N (APN) inhibitors, HIV-l protease inhibitors, and renin inhibitors. The synthesis of α-hydroxy-β-amino acids has therefore attracted considerable interest in recent years and various synthetic approaches have been developed to complete their synthesis. These strategies include utilization of enantiopure starting materials like sugars and amino acids and introduction of bulky groups to achieve the desired stereoselectivity and asymmetric catalysis using enzymes or inorganic catalysts to achieve the desired stereochemistry. This review will discuss these synthetic strategies.