The Progessive and Step-Wise Decarboxylation of Furan-Tetracarboxlic Acid

Tetra-ethyl furantetracarboxylate is readily prepared by the condensation of oxalacetic ester. The corresponding furantetracarboxylic acid can be progressively decarboxylated. Two of the interesting products of decarboxylation are 3, 4-furandicarboxylic acid and 3-furoic acid. The 3, 4-furandicarboxylic acid is interesting not only for purposes of absolute orientation (it completes the series of furandicarboxylic acids) but also because it gives unequivocal evidence for the constitution of a series of 2-nitrofurans. It now appears that this method of stripping carboxyl groups is the best now available for the synthesis of 3-furoic acid, which otherwise is prepared with considerable difficulty