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

Abstract

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