From seed oil of Helichrysum bracteatum Andr., Compositae: R. G. Powell et al., J. Am. Oil Chem. Soc. 42, 165 (1965). Structure: eidem, J. Org. Chem. 30, 610 (1965). Absolute configuration: J. C. Craig et al., ibid. 4342. Partial synthesis of racemic helenynolic acid: H. R. S. Conacher, Gunstone, Lipids 5, 137 (1970). Synthesis of (±)-form: T. B. Patrick, G. F. Melm, J. Org. Chem. 44, 645 (1979).