Design and Synthesis of Novel Fluoropeptidomimetics as Potential Mimics of the Transition State during Peptide Hydrolysis

α-Fluoroamino acids were targeted in our ongoing efforts to design novel fluoropeptidomimetics (1) as potential protease inhibitors. α-Fluoroglycine derivative (2) and α-fluoro-β-aminoethanethiol derivatives (3−9) were synthesized for the first time en route to obtain the peptidomimetic moiety 1. The stability of 2−9 was investigated under organic as well as aqueous conditions. The stability of 3−9 under acidic and basic conditions, the effect of substitution at C-2 position, and potential biological activities are discussed.