Showing papers on "Flavanone published in 1971"

Flavonoids in Citrus and Related Genera

Abstract: The occurence and distribution of flavonoid glycosides in young leaves and young and mature fruits of many citrus species and trifoliate orange were investigated. The occurence of neohesperidin in both young leaves and young fruits is fairly common to a number of species in subgenus Archicitrus. Ripe fruits of citrus could be classified into (a) the hesperidin group (b) the neohesperidin group (c) the naringin group and (d) the isonaringin group. A new flavanone glycoside, isonaringin, isolated from young fruits of Jagatarayu and Teng mikan is slightly bitter and has been determined by chemical and spectral evidences to have the structure of naringenin-7-rhamnoglucoside. Data showing the occurence of flavanone glycosides in some artificial citrus hybrids were also given.

Synthese des 7‐β‐Neohesperidosyl‐4′‐β‐D‐glucopyranosylnaringenins, eines Flavanontriglykosids aus Citrusfrüchten

Abstract: Das von Mizelle und Mitarbb. aus Citrus paradisi Macf. isolierte 7-β-Neohesperidosyl-4′-β-D-glucopyranosyl-naringenin (3) wurde durch Kondensation von Phloracetophenon-4-β-neohesperidosid (1) mit 4-Hydroxy-benzaldehyd-4-β-D-glucopyranosid (2) und Cyclisierung des entstandenen Chalkonglykosids synthetisiert. Durch Dehydrierung des Flavanontriglykosid-undecaacetats (3a) wurde nach Verseifen das 7-β-Neohesperidosyl-4′-β-D-glucopyranosyl-apigenin (7) als erstes synthetisches Apigenintriglykosid dargestellt. Synthesis of 7-β-Neohesperidosyl-4′-(β-D-glucopyranosyl)naringenin, a Flavanone Triglycoside from Citrus Fruits The glycoside 7-β-neohesperidosyl-4′-(β-D-glucopyranosyl)naringenin (3), isolated from the segments of Citrus paradisi Macf, by Mizelle et al., was synthesized by condensation of phloracetophenone 4-β-neohesperidoside (1) with 4-hydroxybenzaldehyde 4-β-D-glucopyranoside (2) and by cyclisation of the resulting chalkone glykoside. Dehydrogenation of the flavanone triglykoside undecaacetate and subsequent saponification leads to the formation of 7-β-neohesperidosyl-4′-(β-D-glucopyranosyl)apigenin (7), the first synthetic apigenin triglycoside.

Selective esterification, substitutions (SN1), and transformations of flavan-3,3′,4,4′,7-pentaols

Abstract: The 3- and 4-monoacetates of (+)-3′,4′,7-trimethoxy-2,3-trans-flavan-3,4-trans-diol have been prepared for the first time. These compounds show different mass spectral fragmentation patterns.Substitutions by primary alcohols result in mixtures (1 : 2) of 2,3-trans-3,4-trans- and 2,3-trans-3,4-cis-4-alkyl ethers irrespective of whether the trimethyl ethers of the 3,4-trans- or the 3,4-cis-flavan-3,4-diols are used as reactants. The 3-acetates of 2,3-trans-3,4-cis-4-alkyl ethers have an unusual twist-boat conformation.Treatment of (+)-flavan-3,3′,4,4′,7-pentaol with mercaptoacetic acid results in similar substitution restricted to the 4-position, without heterocyclic ring fission. When access of air is permitted, optically pure dihydroflavonol and flavanone analogues are formed in prominent side reactions. The mechanism of their formation is discussed.

Mechanism of the conversion of flavan-3,4-diols into dihydroflavonols and flavanones in acid medium

Abstract: Substitution reactions of mercaptoacetic acid with 2,3-trans- and 2,3-cis-flavan-3,4-diols and 2,3-trans-flavan-[4-2H]-3,4-diols illustrate the mechanism of their conversion into dihydroflavonol and flavanone analogues as side-reactions.