Directed Metalation of Heterocycles, 5-Methoxy-2-phenyloxazol-4-yllithium: An Approach toα,β-Dehydroamino Acids

摘要

5-Methoxy-2-phenyloxazole was deprotonated atC4(byn-BuLi or LDA, in THF at −78C∘). The resulting anion was generally unreactive to alkylation (except methylation with MeI-TMEDA) but added to PhCHO andMe2CHCHO. The alcohols thus produced dehydrated and ring opened in acid, to the correspondingα,β-dehydroamino acids in moderate overall yields.