A new and general method for the synthesis of podoblastin derivatives and 3-acyltetronic acids via isoxazoles is described. The key isoxazole intermediates were obtained by 1, 3- dipolar cycloaddition reaction of acetylenecarboxylic acid derivatives to nitrile oxides. These isoxazoles were readily converted to the title compounds by hydrogenolysis followed by hydrolysis and cyclization.
