Direktsynthese von 5,7‐ Dihydroxy‐6‐methoxyflavonen. II. Synthesen von Flavonen aus Eupatorium‐Arten, II

Abstract

~~_ _ _ ~ ~Von den funf bisher noch nicht synthetisch dargestellten Flavonen und Flavonolen aus Eupatorium-Arten wurden Eupatilin (5,7-Dihydroxy-3',4.6-trimethoxytlavon) (2a) nach der StOz-Oxidations-Methode, Eupalitin (3,4,5-Trihydroxy-6,7-dimethoxytlavon) (4n). Eupatolitin (3,3',4,S-Tetrahydroxy-6.7-dirnethoxyflavon) (Sn), Eupatoretin (3,3'-Dihydroxy-4',5,6,7tetramethoxyflavon) (a) und Eupatin (3,3',5-Trihydroxy-4',6,7-trimethoxyflavon) (7) aus den entsprechenden Chalkonen nach einer modifizierten AFO-Oxidations-Methode synthetisiert und in ihrer Struktur bewiesen.Direct Syatbesis of 5,7-Dihydroxyd-methoxyIiavae~s, I1 1) Syntbesii of F t a v m s from Enputorivm species,From the five flavones and flavonols isolated from Euparorium species and not synthesized hitherto the following compounds were synthesized and confirmed in their structures: eupatilin (5,7-dihydroxy-3',4,6-trimethoxyflavone) (213) by the SeO2-oxidation method, eupalitin (3.4,5-tri hydroxy-6,7dimethoxyfiavone) (4a), eupatolitin (3,3',4.5 tetrahydroxy-6,7dimethoxyflavone) (Sn), eupatoretin (3,3'-dihydroxy-4',5,6,7-tetramethoxyflavone) (6). and eupatin (3,3',5-trihydroxy-4',6,7-trimethoxyflavone) (7) by a modified AFO-oxidation of the corresponding chalkones.Kupchan und Mitarbb.4-6) isolierten im Jahre 1969 aus den oberirdischen Teilen von Eupatorium semiserratum D. C. je zwei Flavone und Flavonole mit cytotoxischer Wirkung. Die Flavonoide, alle 5,6,7-substituiert, mit einer Methoxy-Gruppe an C-6, nannten sie Eupatorin (l), Eupatilin (2a), Eupatoretin (6) und Eupatin (7). Diese Reihe wird durch zwei weitere Flavonole erganzt, von Quijano und Mitarbb.7) im Jahre 1970 1) I.

Two New Flavones in Citrus reticulata

“…358 (M+) (17), 343 (100), 181 (6), 162 (4); nmr (CDClj, 270 MHz) 3.96, 3.97, 3.99, 4.02 (12H, each s, 4XOCH3), 6.59 (1H, s, H-3), 6.89 (1H, s, H-8), 6.97 (1H, d J=8.56 Hz, H-5'), 7.37 (1H, d,J=2.13 Hz, H-2'), 7.50(1H, dd,7=8.56, 2.13 Hz, H-6'); uv X max (MeOH) (log e) 265 sh (4.13), 330 Synthesis of 1. -4' -Benzyloxy-2' -hydroxy-3,4,5',6' -tetramethoxychalcone [3], mp 167-168°[lit. (4) mp 148-150°], (1.0 g, 2.2 mmol) was heated in a dry dioxane solution (30 ml) containing DDQ (1.0 g, 4.4 mmol) under reflux for 30 h. The reaction mixture was purified with column chromatography on Si gel (eluent: «-C^H^-EtOAc, 1:1) to give 4 (380 mg) as colorless needles, mp 176-177°.…”

“…Thus, 1 was presumed to be 7-hydroxy-3',4', 5,6-tetramethoxyflavone (2-4) and confirmed by total synthesis. 4'-Benzyloxy-2'hydroxy-3,4,5',6' -tetramethoxy chalcone [3] (4) was converted to 7-benzyloxy-3', 4',5,6-tetramethoxy flavone [4] by oxidation with 2,3 -dichloro-5,6-dicyanobenzoquinone (DDQ). The position of the hydroxy was suggested to be at C-3' by the bathochromic shift (48 nm) with decreasing intensity on addition of NaOMe in the uv spectrum.…”

A New Flavanone from the Leaves of Chromolaena odorata

“…This was confirmed by the HMBC correlations, as summarized in Figure 1. A perusal of the literature on chalcones indicates, that the data correlates closely to the structure of chalcone 3,2'-dihydroxy-4,4,5,6-tetramethoxychalcone reported as a synthetic byproduct, but no data was furnished [29]. To the best of our knowledge this is the first report of its isolation from a natural source.…”

Constituents of Rudbeckia serotina

“…Chromatography of this material on silica gel gave, in order of elution, 3,4',5-trihydroxy-3',6,7trimethoxyflavone (3 mg) (4), eupalitin (6 mg) (3), and eupatolitin (81 mg) (3). Rechromatography of the eupatolitin mother liquors gave sodium salicylate (3 This book is another volume in the series "Bausteine der modernen Physiologic.…”