4-fluoro-3- methylpentanoates () which were converted to their carbanions. Treatment with bromine gave esters , and iodine gave alkyl 4-fluoro-2-iodo- 3-methylpentanoates (). Esters and were converted to alkyl 2-azido-4-fluoro-3-methylpentanoates () whose hydrogenation gave alkyl 2-amino-4-fluoro-3-methylpentanoates (). Hydrolysis afforded γ-fluoroisoleucine ().