4626. Helenalin
Nomenclature
CAS number: 6754-13-8
[3aS-(3aα,4α,4aβ,7aα,8α,9aα)]-3,3a,4,4a,7a,8,9,9a-Octahydro-4-hydroxy-4a,8-dimethyl-3-methyleneazuleno[6,5-b]furan-2,5-dione; 6α,8β-dihydroxy-4-oxoambrosa-2,11(13)-dien-12-oic acid 12,8-lactone. C15H18O4; mol wt 262.30.
C 68.68%, H 6.92%, O 24.40%.
Description and references
Pseudoguaianolide sesquiterpenoid lactone from Helenium autumnale L., H. amarum (Raf.) H. Roch, H. microcephalum DC., Compositae. Isoln: Clark, J. Am. Chem. Soc. 58, 1982 (1936); and characterization: Adams, Herz, ibid. 71, 2546 (1949). Structure: Büchi, Rosenthal, ibid. 78, 3860 (1956); Barton, de Mayo, Q. Rev. Chem. Soc. 11, 189 (1957); Herz, J. Org. Chem. 27, 4043 (1962). Abs config studies: Herz, Kagan, ibid. 32, 216 (1967). Synthesis of racemic form: Y. Ohfune et al., J. Am. Chem. Soc. 100, 5946 (1978); M. R. Roberts, R. H. Schlessinger, ibid. 101, 7626 (1979); C. H. Heathcock et al., ibid. 104, 1907 (1982). Toxicity study: D. A. Witzel et al., Am. J. Vet. Res. 37, 859 (1976).
Properties
Bitter, sternutative crystals from benzene, mp 167-168°. [α]D25 102.8° (c = 3.64 in 95% ethanol). uv max: 223 nm (ε 11900). Slightly sol in water; sol in alcohol, chloroform, hot benzene. LD50 in mice, rats (mg/kg): 150, 125 orally (Witzel).Derivative
Acetylhelenalin.C17H20O5; mol wt 304.34.
C 67.09%, H 6.62%, O 26.29%.