THE STRUCTURES OF EUPALIN AND EUPATOLIN. TWO NEW FLAVONOL RHAMNOSIDES ISOLATED FROM EUPATORIUM LIGUSTRINUM DC.* L. QUIJANo,t F. MALANCot and Tmso Rfos Contribution No. 305 from Institute de Quimica de la Universidad National Autonoma de Mexico, Mtxico 20, D.F. (Received in the USA 4 November 1969 ; Received in the UK for publication 19 December 1969) Abstract-Two new flavonols, eupalitin and eupatolitin were isolated from Eupatorium ligustrinum D.C. as their rhamnosides. The structure of eupalitin (II) was established as the 3,5,4’-trihydroxy_6,7dimethoxy- Ravone and that for eupatolitin (IX) as 3,5,3’,4’-tetrahydroxy6,7 dimethoxyflavone. In eupalin and eupatolin a rhamnose molecule is attached at the 3 position. Eupatorium ligustrintun D.C., a member of the Compositae family is a shrub that grows near Jalapa, Ver. In previous paper we have reported the isolation of the guaianolide ligustrin,’ and now from the ethanol extract of the aereal parts of the plant, eupalin (I) and eupatolin (VIII) were isolated. Eupalin (I) is a crystalline yellow compound Cz3Hz40,, m.p. 207-210”; [aID -129” (pyridine): v,, 1670 cm-’ (a&unsaturated CO); &_: 273,34Omp, e, 1540814518. Acetylation of eupalin (I) in acetic anhydride-perchloric acid afforded the penta- acetoxy compound C3JH34016 (la) m.p. 119-121”, v, 1768 and 1628 cm-’ (phenolic acetyl groups and a&unsaturated CO). The NMR spectrum of compound Ia exhibits signals at @82 (d) for Me group: at 1.92, 1.95, 2.16, 2.24 and 2.34 due to the five acetyl groups: 3.18 (broad signal) for one H on the C atom bearing the oxygen: 3.71 and 384 for the two OMe groups; a complex signal between 4.6 and 5.7 corresponds to four hydrogens, three of them on the carbons bearing the three OAc groups and the fourth on the carbon supporting the glycosidic linkage. The singlet at 6.72 is assigned to one aromatic proton. In addition it exhibits two doublets at 7.12 (d) and 7.81 (d) (J = 8 c/s) due to four protons that were involved in an AzBz system. The NMR spectra data for eupalin and its derivatives are given in Table 1. From the mother liquors of a prolonged acetylation of eupalin in acetic anhydride perchloric acid it was isolated the acetate of a carbohydrate which proved to he identical with that obtained from an authentic sample of rhamnoset by IR and NMR comparisons. From the empirical formula, specific color reactions and specially from the NMR spectrum of acetate la, we came to the conclusion that the eupalin is a flavonoid glycoside. l We wish to thank H. Quero of the Institute de BiologIa of U.N.A.M. for a collection and identification of the plant. t Taken in part from the theses submitted to the Facultad de Quhnica (UNAM) for L. Quijano and F. Malanco. $ Kindly supplied by Dr. Barbarin Arm&n from this Institute. 2851