2-Methyl-(1Z,3E)-butadiene-1,3,4-tricarboxylic acid, "isoprenetricarboxylic acid".

[reaction: see text] The synthesis of the title compound 7 from ethyl glyoxylate and dimethyl and diethyl beta-methylglutaconate is described along with its physical properties that suggest its inability to assume a cis-dienoid structure due to steric hindrance between the methyl and carboxyl groups.