Simple Stereospecific Syntheses of (R)-2-Fluorohexanoic Acid Ethyl Ester

Simple stereospecific syntheses of 2-fluorohexanoic acid 5 were accomplished by conversion of optically pure L-(+)-norleucine to the optically pure hydroxy acid 3 via the classic diazotization reaction followed by substitution of the hydroxy functionality by the fluoro group. This was accomplished stereospecifically using DAST reagent or more practically by nucleophilic displacement of the corresponding mesyloxy group with fluoride ion.