Synthesis of sophorol, violanone, lonchocarpan, claussequinone, philenopteran, leiocalycin, and some other natural isoflavonoids by the oxidative rearrangement of chalcones with thallium(<scp>III</scp>) nitrate

Farkas, L.; Gottsegen, Á.; Nóagrádi, Mihàly; Antus, Sándor

doi:10.1039/p19740000305

Cited by 87 publications

(17 citation statements)

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“…A series of these compounds (52)(53)(54)(55)(56)(57) (Table 4) were prepared in racemic form using different methods described in the literature [52][53][54] and then their resolutions were achieved by CD monitored HPLC using chiral stationary phase. 55 In agreement with our former results, 56 the dextrorotatory enantiomers of the studied compounds [(+)-52-57] were eluted first, followed by the levorotatory ones whose 1 L b and 1 L a band CD data are listed in Table 4.…”

Section: Pterocarpan Chromophorementioning

confidence: 99%

Chiroptical properties of 2,3‐dihydrobenzo[b]furan and chromane chromophores in naturally occurring O‐heterocycles

et al. 2001

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The correlation between the helicity (absolute conformation) of the O-heterocyclic ring of chiral 2,3-dihydrobenzo[b]furan (1) and chromane (2) derivatives and their (1)L(b) band CD was investigated. The same helicity rule was found for both unsubstituted chromophores: P/M helicity of the heterocyclic ring leads to a negative/positive CD within the (1)L(b) band. While the substitution of the fused benzene ring by achiral substituents does not change this helicity rule for the chromane chromophore, it leads to its inversion for the 2,3-dihydrobenzo[b]furan chromophores. On the basis of these observations, the published absolute configurations of natural flavonol and pterocarpan derivatives were confirmed and the configurational assignments of several natural neolignans revised.

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Section: Pterocarpan Chromophorementioning

confidence: 99%

Chiroptical properties of 2,3‐dihydrobenzo[b]furan and chromane chromophores in naturally occurring O‐heterocycles

et al. 2001

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“…Oxidative rearrangement of acetate 10, prepared from 9, with thallium(III) nitrate trihydrate (TTN), 20) followed by hydrolysis of the resulting mixture 11 with aqueous sodium hydroxide gave the desired 6-iodoisoflavone 12 in 40% yield and the chalcone 9, the structures of which were identified by 1 H-NMR spectral analysis. On the basis of the results, it was shown that deacetylation of 10 with TTN took place more easily than the oxidative rearrangement of the phenyl group of 10 to give the chalcone 9.…”

Section: Resultsmentioning

confidence: 99%

“…14) Condensation of 7 with 2,4-bis(benzyloxy)benzaldehyde in the presence of sodium hydroxide gave 6Ј-methoxymethoxychalcone 8, and then the methoxymethyl group in the chalcone was cleaved by treatment with dilute HCl to give 3Ј-iodo-6Ј-hydroxychalcone 9 in 86% yield. Oxidative rearrangement of acetate 10, prepared from 9, with thallium(III) nitrate trihydrate (TTN), 20) followed by hydrolysis of the resulting mixture 11 with aqueous sodium hydroxide gave the desired 6-iodoisoflavone 12 in 40% yield and the chalcone 9, the structures of which were identified by 1 H-NMR spectral analysis. On the basis of the results, it was shown that deacetylation of 10 with TTN took place more easily than the oxidative rearrangement of the phenyl group of 10 to give the chalcone 9.…”

Section: Resultsmentioning

confidence: 99%

Regioselective Synthesis of 6-Alkyl- and 6-Prenylpolyhydroxyisoflavones and 6-Alkylcoumaronochromone Derivatives

Tsukayama

Wada

Kawamura

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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Prenyl (ϭ3-methyl-2-butenyl)isoflavones and (3-hydroxy-3-methylbutyl)isoflavones, which contain an alkyl or alkenyl group in the A-and/or B-ring, are widely distributed in nature and have antifungal activity. [1][2][3][4] Luteone, known as a phytoalexin, was first isolated in 1973 from immature fruits of Lupinus luteus (Leguminosae).5) The structure was assigned as 2Ј,4Ј,5,7-tetrahydroxy-6-(3-methyl-2-butenyl)isoflavone (1) by spectroscopic and chemical studies. The same isoflavone 1 was also isolated from healthy leaves or roots of white lupin (Lupinus albus L., cv Kievskij Mutant) 4,6) and the roots of yellow lupin (Lupinus leuteus L., cv. Barpin) together with luteone hydrate, the structure of which was assigned to be 2Ј,4Ј,5,7-tetrahydroxy-6-(3-hydroxy-3-methylbutyl)isoflavone (2) by spectroscopic analysis.7) Luteone hydrate (2) was isolated as a fungal metabolite of luteone (1) with cultures of Aspergillus flavus and Botrytis cinerea. 8)Wighteone hydrate [4Ј,5,7-trihydroxy-6-(3-hydroxy-3-methylbutyl)isoflavone] (3) was also isolated as a fungal metabolite of wighteone [4Ј,5,7-trihydroxy-6-(3-methyl-2-butenyl)isoflavone] 2,6,7,9) with cultures of A. flavus and B. cinerea. 10) In view of the isolation of 1 and 2 from the same natural source, it is considered that 2 is a precursor of 1 and dehydration of 2 would lead to 1. The total syntheses of isoflavones 1, 2, and 3 have not been achieved yet, although the dimethyl ether of luteone (1) has been synthesized.11) The reason seems to be due to the difficulty in introducing an alkyl or alkenyl group regioselectively into the isoflavone nucleus and the selectivity of protection and consequent deprotection. Furthermore, 6-alkylpolyhydroxyisoflavones are isomerized to the corresponding isomers, 8-alkylpolyhydroxyisoflavones, by bases.12,13) We need to solve these problems for the regioselective synthesis of these phloroglucin-type 6-prenylisoflavones. In our previous paper, 14) we reported the regioselective synthesis of prenylisoflavones. As a continuation of our studies on the regioselective synthesis of alkyl-and prenylisoflavones, we wish to report here on the first syntheses of 1, 2, and 3 using the palladium (0)-catalyzed coupling reaction 15) of the corresponding iodoisoflavone with 2-methyl-3-butyn-2-ol.16) Recently, the new coumaronochromones (ϭbenzofuro [2,3-b][1]benzopyran-11-ones) lupilutin (8-alkylcoumaronochromone from the root of yellow lupin) 7) and lupinalbin B (6-prenylcoumaronochromone from the root of white lupin) 17) have also been isolated. However, 6-alkylcoumaronochromone (4), which is considered to be a precursor of lupinalbin B, has yet to be isolated from natural sources. We have examined the simple and general applicability of DDQ or o-chloranil to the synthesis of alkylpolyhydroxycoumaronochromones from the corresponding 2Ј-hydroxyisoflavones. 18) We wish to report here the synthesis of compound 4 by oxidative cyclization of compound 2 with ochloranil. Results and DiscussionThe catalytic hydrogenation of 2Ј,4Ј-bis(benzyloxy)-6Ј-methoxym...

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“…The resulting compound was chromatographed on a silica-gel column (CHCl 3 :Me 2 CO 15 : 1) to give the 6-prenylisoflavone 14, which was recrystallized from a mixture of CHCl 3 and Me 2 CO (5 : 1) to give 14 (554 mg, 57% from 13) as a crystalline solid, mp 202 -2048C. 1 4 0 ,7-Bis(benzoyloxy)-5-hydroxy-6-(3-methyl-2-butenyl)isoflavone (15): Compound 14 (400 mg, 0.57 mmol) was dissolved in dry CH 2 Cl 2 (10 ml), followed by the addition of BCl 3 (0.58 ml, 1 M solution in CH 2 Cl 2 ) in an ice bath. The reaction mixture was stirred at 20-258C under nitrogen for 2.5 h. The resulting mixture was quenched with saturated NH 4 Cl solution, extracted with CH 2 Cl 2 , washed with water, and dried (Na 2 SO 4 ).…”

Section: -[6-benzoyloxy-24-bis(benzyloxy)-3-iodophenyl]-2 -[4-benzymentioning

confidence: 99%

“…3H 2 O, thallium(III) nitrate trihydrate (TTN). [15,16] Wighteone hydrate 2 was synthesized by oxidative rearrangement of the corresponding 3 0 -iodochalcone with TTN in low yield. [17] 5,7-Bis(benzyloxy)-6-iodo-3 0 ,4 0 -methylenedioxyisoflavone was also obtained by the oxidative rearrangement of the corresponding chalcone with TTN in low yield (17%).…”

Section: Regioselective Synthesis Of 6-prenylpolyhydroxyisoflavone (Wmentioning

confidence: 99%

Regioselective Synthesis of 6‐Prenylpolyhydroxyisoflavone (Wighteone) and Wighteone Hydrate with Hypervalent Iodine

Hossain

Tokuoka

Yamashita

et al. 2006

Synthetic Communications

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Synthesis of sophorol, violanone, lonchocarpan, claussequinone, philenopteran, leiocalycin, and some other natural isoflavonoids by the oxidative rearrangement of chalcones with thallium(III) nitrate

Cited by 87 publications

References 0 publications

Chiroptical properties of 2,3‐dihydrobenzo[b]furan and chromane chromophores in naturally occurring O‐heterocycles

Chiroptical properties of 2,3‐dihydrobenzo[b]furan and chromane chromophores in naturally occurring O‐heterocycles

Regioselective Synthesis of 6-Alkyl- and 6-Prenylpolyhydroxyisoflavones and 6-Alkylcoumaronochromone Derivatives

Regioselective Synthesis of 6‐Prenylpolyhydroxyisoflavone (Wighteone) and Wighteone Hydrate with Hypervalent Iodine

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