α,β-Unsaturated Carboxylic Acid Derivatives. XII. A Convenient Synthesis of Oxazole-4-carboxylic and 3,3-Dibromo-2,2-diamino Acids

Treatment of t-butyl 2-acetylamino-3-bromo-2-alkenoate with triethylamine gave t-butyl 5-alkyl-2-methyloxazole-4-carboxylate by dehydrobromination, but no reaction occurred with primary amines. While treatment of t-butyl 2-acetylimino-3,3-dibromoalkanoate with hydroxylamine or several aliphatic and aromatic primary amines gave addition products, t-butyl 2-acetylamino-3,3-dibromo-2-(hydroxyamino)- and 2-(substituted amino)alkanoate, respectively, in fairly good yields.