- Synthesis of novel substituted pyrano annulated flavones
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A simple and efficient one pot method has been developed for the synthesis of some new functionalized pyrano fused flavone derivatives, alkyl 4,8-dioxo-2-phenyl-4,8-dihydropyrano[2,3-f]chromene-10-carboxylates and dialkyl 4-oxo-2-phenyl-4,8-dihydropyrano[2,3-f]chromene-8,9-dicarboxylates, from 7-hydroxy flavones and 7-hydroxy 8-formyl flavones using dialkylacetalynedicarboxylates in the presence of triphenyl phosphine. The structures of all synthesized compounds were elucidated by FT-IR, 1H and 13C NMR and Mass spectral analysis.
- Jayaprakash Rao,Thirupathi,Prasad Rao, Ch.,Hemasri
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p. 1126 - 1131
(2016/07/06)
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- Synthesis of Diverse Oxa-Carbocycle-Annulated Flavones Using the Combined Claisen Rearrangement and Ring-Closing Metathesis
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A simple and efficient route for the synthesis of oxepine-, oxocine-, oxepinone-, and dioxocine-angularly annulated flavone skeletons has been developed. The combined Claisen rearrangement and the ring-closing metathesis are used as key steps for the construction of C7/C8–C6–C6tricyclic core structures.
- Gogula, Thirupathi,Yerrabelly, Jayaprakash Rao
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p. 547 - 557
(2016/07/22)
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- Synthesis, in vitro evaluation, and docking studies of novel chromone derivatives as HIV-1 protease inhibitor
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Novel chromone derivatives with a benzopyran-4-one scaffold have been prepared by the one-pot cyclization reaction. The in vitro inhibitory activity of these new compounds towards HIV-1 protease have been evaluated using stop time HPLC method as the preliminary screening. The most potent compound, 7,8-dihydroxy-2-(3′-trifluoromethyl phenyl)-3-(3″- trifluoromethylbenzoyl)chromone (32), showed IC50 = 0.34 μM. The molecular docking study supported results from experimental activity testing and also provided structure-activity relationship of this series.
- Ungwitayatorn, Jiraporn,Wiwat, Chanpen,Samee, Weerasak,Nunthanavanit, Patcharawee,Phosrithong, Narumol
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p. 152 - 161
(2011/10/03)
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- Facile synthesis of 9-acetyl/formyl/cyano-substituted pyrano[2,3-f]flavones and chromones using the baylis-hillman reaction
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Condensation of 8-formyl-7-hydroxyflavones (2a-f) and 8-formyl-7-hydroxy-2- (2'-furyl)-3-methylchromone (2g) with methyl vinyl ketone (3), acrolein (4), and acrylonitrile (5) in the presence of diazabicyclo[2.2.2]octane (DABCO) under an N2 atmosphere at room temperature using Baylis-Hillman reaction conditions afforded 9-acetyl/formyl/cyano-substituted pyrano2,3-f]flavones (6a-f, 7a-f, 8a-f) and chromones (6g, 7g, 8g).
- Reddy, S. Satyanarayana,Krupadanam, G. L. David
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experimental part
p. 1292 - 1304
(2010/06/20)
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- A New Synthesis of 9-Methylfuroflavones
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9-Methylfuroflavones (III) have been synthesised by thermal Claisen rearrangement of 7-propargyloxy flavones (II).
- Prasunamba, P. L.,Srimannarayana, G.
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- Claisen Rearrangement of 7-(3'-Methylbut-2'-enyloxy)flavones and Isoflavones
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The Claisen rearrangement of 7-(3'-methylbut-2'-enyloxy)-3-methylflavone (IIb) in N,N-dimethylaniline yields an abnormal open-chain product 7-hydroxy-8-(1',2'-dimethylallyl)-3-methylflavone (IIIb), the normal cyclisation product 2",3"-dihydro-2",3",3",3-tetramethylfuroflavone (Vb) and 2",3"-dihydro-2",2",3",3-tetramethylfuroflavone (VIb).Rearrangement of IIb in vacuo yields 7-hydroxy-3-methylflavone (Ib) and VIb.The Claisen rearrangement of IIb in Ac2O-NaOAc gives 7-acetoxy-8-(1',1'-dimethylallyl)-3-methylflavone (VIIIb) which on alkaline hydrolysis yields 7-hydroxy-8-(1',1'-dimethylallyl)-3-methylflavone (VIIb) (normal open-chain product).Claisen rearrangement of VIIb gives a mixture of IIIb, Vb and VIb.Rearrangement of 7-(3'-methylbut-2'-enyloxy)flavone (IIa) in N,N-dimethylaniline furnishes 7-hydroxy-8-(1',2'-dimethylallyl)flavone (IIIa) and 2",3"-dihydro-2",3",3"-trimethylfuroflavone (Va).Under similar conditions 7-(3'-methylbut-2'-enyloxy)-3-phenylflavone (IIc) and 7-(3'-methylbut-2'-enyloxy)-2-methylisoflavone (IId) yield only 2",3"-dihydro-2",3",3"-trimethylfuro derivatives (Vc) and (Vd) respectively.Acid-catalysed cyclisation of IIIa, IIIb and VIIIb gives VIa, VIb and Vb respectively.In all the Claisen rearrangements, only the angular rearrangement products (i.e. rearrangement to 8-position of flavonoid nucleus) are isolated.It is believed that unstable 7-hydroxy-8-(1',1'-dimethylallyl) compound (VII) acts as an intermediate for the formation of III, V and VI.
- Subba Raju, K. V.,Sudha, K.,Srimannarayana, G.
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p. 866 - 870
(2007/10/02)
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