The simple compound apparently has yet to be observed (as of 2009). In 1998, however, Paolo Strazzolini and others have claimed the synthesis of dioxane tetraketone (C4O6), which can be viewed as the cyclic dimer of oxalic anhydride.[1]
^Paolo Strazzolini; Alberto Gambi; Angelo G. Giumanini; Hrvoj Vancik (1998). "The reaction between ethanedioyl (oxalyl) dihalides and Ag2C2O4: a route to Staudinger's elusive ethanedioic (oxalic) acid anhydride". J. Chem. Soc., Perkin Trans. 1 (16): 2553–2558. doi:10.1039/a803430c.
^Ahmed A. El-Sherif; Bakir J. A. Jeragh (2007). "Mixed ligand complexes of Cu(II)-2-(2-pyridyl)-benzimidazole and aliphatic or aromatic dicarboxylic acids: Synthesis, characterization and biological activity". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 68 (1): 877–882. Bibcode:2007AcSpA..68..877E. doi:10.1016/j.saa.2006.12.073. PMID17320475.
^M. M. Rauhut; L. J. Bollyky; R. A. Clarke; M. Loy; B. G.Roberts (September 30, 1965). Chemiluminescent Materials (AD0621845)(PDF) (Technical report). Office of Naval Research and Advanced Research Projects Agency. 9. Archived(PDF) from the original on July 22, 2021.