The synthesis of the structural isomers of 6-oxo-2, 4-heptadienoic acid was undertaken as a means of providing analogues to investigate the structural requirements of maleylacetone cis-trans isomerase. 6-0xo-2 (Z), 4 (E)-heptadienoic acid and the methyl esters of 6-oxo-2 (E), 4 (Z)-,~-oxo-~(Z),~(Z)-, and 6-oxo-2 (E), 4 (E)-heptadienoic acid were synthesized. Base- catalyzed hyrolysis of these esters furnished the corresponding acids except in the case of ...