Synthesis of paramagnetic and diamagnetic flavones and flavanones

Kálai, Tamás; Kulcsár, Gyula; Ősz, Erzsébet; Jekő, József; Sümegi, Balázs; Hideg, Kálmán

doi:10.3998/ark.5550190.0005.721

Cited by 13 publications

(7 citation statements)

References 14 publications

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“…Furthermore, a vibrational band at 1574 and 1604 cm −1 ascribed the benzene ring carbon-carbon stretch. These prominent characteristic features indicate the presence of flavones, a class of compounds based on a backbone of 2-phenylchromen-4-one [11] , [17] , [18] , [19] . The presence of alkyl groups was imputed by two vibrational bands at 2850, 2939 and 2974 cm −1 [20] , [21] .…”

Section: Resultsmentioning

confidence: 99%

Crystal Structure Elucidation and Anticancer Studies of (-)-Pseudosemiglabrin: A Flavanone Isolated from the Aerial Parts of Tephrosia apollinea

et al. 2014

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Tephrosia apollinea is a perennial shrublet widely distributed in Africa and is known to have medicinal properties. The current study describes the bio-assay (cytotoxicity) guided isolation of (-)-pseudosemiglabrin from the aerial parts of T. apollinea. The structural and stereochemical features have been described using spectral and x-ray crystallographic techniques. The cytotoxicity of isolated compound was evaluated against nine cancer cell lines. In addition, human fibroblast was used as a model cell line for normal cells. The results showed that (-)-pseudosemiglabrin exhibited dose-dependent antiproliferative effect on most of the tested cancer cell lines. Selectively, the compound showed significant inhibitory effect on the proliferation of leukemia, prostate and breast cancer cell lines. Further studies revealed that, the compound exhibited proapoptotic phenomenon of cytotoxicity. Interestingly, the compound did not display toxicity against the normal human fibroblast. It can be concluded that (-)-pseudosemiglabrin is worthy for further investigation as a potential chemotherapeutic agent.

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Section: Resultsmentioning

confidence: 99%

Crystal Structure Elucidation and Anticancer Studies of (-)-Pseudosemiglabrin: A Flavanone Isolated from the Aerial Parts of Tephrosia apollinea

et al. 2014

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“…With the optimized condition in hand we then wanted to assess the limitations and scope of this copper-free palladium-catalyzed transformation and therefore tested the reaction conditions with a variety of terminal alkynes. Thus, when 3-iodo(thio)flavone ( I , X = O, S)15a was treated with a overall 3.0 equiv of a terminal alkyne ( II , R = alkyl, hydroxyalkyl, etc.) 15b in dimethylformamide (DMF) in the presence of PdCl 2 (PPh 3 ) 2 (0.04−0.05 equiv) and triethylamine (8 equiv) under a nitrogen atmosphere, 3-enynyl-substituted (thio)flavone ( IV ) was obtained (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

“…Although 3-alkynyl analogues III (Sonogashira product) were isolated as minor products (10−15%) in this present coupling reaction, 3-alkynyl thioflavones ( IIIa − j ), however, could be prepared in good to excellent yields by treating Ia or Ib with 1.5−2.0 equiv of a terminal alkyne ( II ) in DMF in the presence of PdCl 2 (PPh 3 ) 2 (0.04 equiv), CuI (0.05 equiv), and triethylamine (8 equiv) under a nitrogen atmosphere (Scheme 2). 3-Alkynyl flavones 15c on the other hand have been prepared in good yields using ( S )-prolinol as a base in DMF−H 2 O 8b and the chemistry has subsequently been employed by others for the synthesis of paramagnetic and diamagnetic flavones 15d. Interestingly, the palladium-mediated coupling of 3-iodoflavone with internal alkynes16a (due to the participation of the neighboring aryl group in reaction cascades) 16b resulted in the formation of annulated products.…”

Section: Resultsmentioning

confidence: 99%

Regio- and Stereospecific Synthesis of Novel 3-Enynyl-Substituted Thioflavones/Flavones Using a Copper-Free Palladium-Catalyzed Reaction

et al. 2005

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[reaction: see text] A variety of 3-enynyl substituted flavones/thioflavones were synthesized via a sequential one-pot procedure using copper-free palladium-catalyzed cross coupling in a simple synthetic operation. The cross coupling between 3-iodo(thio)flavone and a broad range of terminal alkynes was carried out in the presence of Pd(PPh3)2Cl2 and triethylamine to afford the corresponding 3-enynyl derivatives in a regio- and stereoselective fashion. The best results are obtained by employing 3 equiv of the terminal alkynes. The process worked well irrespective of the substituents present on the (thio)flavone ring as well as in the terminal alkynes except arylalkynes. The reaction is quite regioselective, placing the substituent of the terminal alkyne at the far end of the double bond attached with the (thio)flavone ring. The orientation of the (thio)flavonyl and acetylenic moieties across the double bond was found to be syn in the products isolated. A tandem C-C bond-forming reaction in the presence of palladium catalyst rationalized the formation of coupled product. The catalytic process apparently involves heteroarylpalladium formation, regioselective addition to the C-C triple bond of the terminal alkyne, and subsequent displacement of palladium by another mole of alkyne. The present methodology is useful for the introduction of an enynyl moiety at the C-3 position of flavones and thioflavone rings to afford novel compounds of potential biological interest. In the presence of CuI the process afforded 3-alkynyl (thio)flavones in good yields.

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“…The combined organic phase was dried (MgSO 4 ), filtered and evaporated and after flash chromatography (hexane/EtOAc, 2:1) the title compound was obtained as a white crystalline solid 592 mg (55%), mp 87-89 °C, R f 0.52 (hexane/EtOAc, 2:1), IR (nujol) 1755 (C@O), 1580 (C@C). MS (EI) m/z (%): 359 (M + , 1), 344 (16), 302 (100), 43 (39). 1…”

Section: (E)-1-acetoxymentioning

confidence: 99%

“…Several studies indicated that modificating cardiopotective agents, 13 PARP-inhibitors 14 with nitroxides had a beneficial influence on their activity as supplemented by 'in status nascendi acting' antioxidants and radical scavengers. Chromones and flavones 15,16 modified by nitroxides were reported previously from our laboratory, although the biological activity of these 'hybrid' compounds was not outstanding. To access the influence of the nitroxide on antioxidant activity of resveratrol, paramagnetic analogues of resveratrol were synthesized.…”

Section: Introductionmentioning

confidence: 96%