Title: Secalonic Acids
Molecular Formula: C32H30O14
Molecular Weight: 638.57
Percent Composition: C 60.19%, H 4.74%, O 35.08%
Literature References: Toxic mold metabolites which are diastereoisomeric dimeric hydroxanthone derivatives manifest as yellow pigments. First isolation studies: Stoll et al., Helv. Chim. Acta 35, 2022 (1952). Seven isomers have been isolated: secalonic acid A, secalonic acid B, and secalonic acid C from ergot: Aberhart et al., Tetrahedron 21, 1417 (1965); Franck et al., Ber. 99, 3842, 3875 (1966); secalonic acid D from Penicillium oxalicum: Steyn, Tetrahedron 26, 51 (1970); secalonic acid E from Phoma terrestris: Hansen, Howard et al., Chem. Commun. 1973, 464; secalonic acid F from Aspergillus aculeatus: R. Andersen et al., J. Org. Chem. 42, 352 (1977); secalonic acid G from Pyrenochaeta terrestris: I. Kurobane, L. C. Vining, Tetrahedron Lett. 1978, 4633. Secalonic acid A is enantiomeric with D; secalonic acid B is enantiomeric with E. Chromatographic separation of the ergot pigments: Franck, Angew. Chem. Int. Ed. 8, 251 (1969); structures: ApSimon et al., J. Chem. Soc. 1965, 4144. Revised structures of secalonic acids A, B, C, D: Hooper et al., Chem. Commun. 1971, 111; eidem, J. Chem. Soc. C 1971, 3580. Crystal and molecular structure of secalonic acid A: C. C. Howard et al., J. Chem. Soc. Perkin Trans. 1 1976, 1820. Identity of secalonic acid A with entothein: Yoshioka et al., Chem. Pharm. Bull. 16, 2090 (1968). Biosynthesis of secalonic acid A: I. Kurobane et al., Tetrahedron Lett. 1978, 1379. Review of secalonic acids and other ergochromes: Franck, Flasch in Fortschr. Chem. Org. Naturst. 30, 151-206 (1973).
Derivative Type: Secalonic acid A
CAS Registry Number: 35287-72-0
CAS Name: (3R,3¢R,4S,4¢S,4aS,4¢aS)-2,2¢,3,3¢,4,4¢,9,9¢-Octahydro-1,1¢,4,4¢,8,8¢-hexahydroxy-3,3¢-dimethyl-9,9¢-dioxo-[7,7¢-bi-4aH-xanthene]-4a,4¢a-dicarboxylic acid dimethyl ester
Additional Names: 6,6¢,7,7¢-tetrahydro-1,1¢,5b,5¢b,8,8¢-hexahydroxy-6a,6¢a-dimethyl-9,9¢-dioxo-[2,2¢-bixanthene]-10ab,10¢ab(5H,5¢H)-dicarboxylic acid dimethyl ester; ergochrome AA(2,2¢)
Properties: Fine lemon-yellow needles from dioxane + petr ether + chloroform, mp 246-248° (dec); also reported as mp 260° (Yoshioka et al., loc. cit.). [a]D -73° (CHCl3). uv max (methanol): 247, 340 nm (e 18140, 31200). pKDMF 8.7. Readily soluble in pyridine, dimethylformamide, dioxane; moderately sol in chloroform, methylene chloride, acetone. Gives a wine-red color reaction with 5% FeCl3 in methanol.
Melting point: mp 246-248° (dec); mp 260° (Yoshioka et al., loc. cit.)
pKa: pKDMF 8.7
Optical Rotation: [a]D -73° (CHCl3)
Absorption maximum: uv max (methanol): 247, 340 nm (e 18140, 31200)
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