Abstract
Exptl. evidence is recorded which establishes the constitution of the permanganate oxidation product of mycophenolic acid monomethyl ether as the anhydride of 3,4,5-tricarboxy-2,6-dimethoxyphenylglyoxylic acid. The Na salt of this acid, on further oxidation with H2O2, gives the anhydride of 4,6-dimeth-oxybenzene-l,2,3,5-tetracarboxylic acid which was believed by Clutterbuck and Raistrick (1933) to be the structure of the permanganate oxidation product of mycophenolic acid mono-methyl ether. This evidence confirms the preferred structure advanced for mycophenolic acid by Birkinshaw et al. (1948).