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