Prepd by oxidation of sebacoin with chromium trioxide in acetic acid: Blomquist et al., J. Am. Chem. Soc. 74, 3640 (1952); cf. Prelog et al., Helv. Chim. Acta 35, 1610 (1952); Blomquist, Goldstein, Org. Synth. coll. vol. IV, 838 (1963).