Base-mediated reactions of N-alkyl-O-acyl hydroxamic acids: synthesis of 3-oxo-2,3-dihydro-4-isoxazole carboxylic ester derivatives

Treatment of malonyl derived O-acyl hydroxamic acid derivatives 10a–h with the phosphazene super base P-2-t-Bu 7 gives 2,3-dihydro-4-isoxazole carboxylic ester derivatives 11a–h. The rate and yield of the reaction is dependent upon the O-acyl substituent.