Synthesis and reactions of α-fluoro-α-amino amides

N-((S)-1-Phenylethyl)halofluoroethanamides have been investigated as precursors to N-protected alpha-fluoro-alpha-amino amides by nucleophilic displacement of halide with nitrogen nucleophiles such as potassium phthalimide, sodium succinimide, sodium glutarimide, trimethylamine and sodium azide. With single diastereoisomers; of the iodofluoroethanamide, clean inversion of configuration occurs at room temperature, but subsequent epimerisation may occur as a result of the liberated iodide. The alpha-fluoro-alpha-amino amides made underwent a wide variety of reactions depending on conditions, but in many cases the carbon-fluorine bond was compromised. However, reacting trimethylamine and N-((S)-1-phenylethyl)iodofluoroethanamide gave the corresponding alpha-fluorobetaine amide, and subsequent acidic hydrolysis led to alpha-fluorobetaine as the first example of an 'unprotected' alpha-fluoroamino acid. (C) 2008 Elsevier Ltd. All rights reserved.