Title: Helenalin
CAS Registry Number: 6754-13-8
CAS Name: [3aS-(3aa,4a,4ab,7aa,8a,9aa)]-3,3a,4,4a,7a,8,9,9a-Octahydro-4-hydroxy-4a,8-dimethyl-3-methyleneazuleno[6,5-b]furan-2,5-dione
Additional Names: 6a,8b-dihydroxy-4-oxoambrosa-2,11(13)-dien-12-oic acid 12,8-lactone
Molecular Formula: C15H18O4
Molecular Weight: 262.30
Percent Composition: C 68.68%, H 6.92%, O 24.40%
Literature 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°. [a]D25 -102.8° (c = 3.64 in 95% ethanol). uv max: 223 nm (e 11900). Slightly sol in water; sol in alcohol, chloroform, hot benzene. LD50 in mice, rats (mg/kg): 150, 125 orally (Witzel).
Melting point: mp 167-168°
Optical Rotation: [a]D25 -102.8° (c = 3.64 in 95% ethanol)
Absorption maximum: uv max: 223 nm (e 11900)
Toxicity data: LD50 in mice, rats (mg/kg): 150, 125 orally (Witzel)
Derivative Type: Acetylhelenalin
Molecular Formula: C17H20O5
Molecular Weight: 304.34
Percent Composition: C 67.09%, H 6.62%, O 26.29%
Properties: Crystals from aq methanol, mp 184°. uv max: 221, 316 nm (e 12600, 61).
Melting point: mp 184°
Absorption maximum: uv max: 221, 316 nm (e 12600, 61)
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