- Metal-free methodology for the preparation of sterically hindered alkynoylphenols and its application to the synthesis of flavones and aurones
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A metal-free synthesis for the preparation of sterically demanding ortho-demethylated ynones from mixed anhydrides and potassium alkynyltrifluoroborate salts has been developed. The one-pot reaction proceeds rapidly in the presence of a Lewis acid without the exclusion of air and moisture. This method is advantageous in that it is operationally simple, proceeds under mild conditions, and has a broad substrate scope. 2,6-Dimethoxy substituted anhydrides afford the corresponding mono-demethylated ynone products in good yields. In particular, 2-hydroxy substituted ynone products are valuable synthetic intermediates because their conversion to biologically active natural product scaffolds is straightforward. Flavones were obtained via 6-endo cyclization of the o-alkynyoylphenol intermediates under acidic conditions. Cesium carbonate was found to promote rapid 5-exo cyclization to furnish aurone products.
- Taylor, Cassandra,Bolshan, Yuri
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p. 4392 - 4396
(2015/06/22)
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- Synthesis and inhibitory activity against COX-2 catalyzed prostaglandin production of chrysin derivatives
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A series of chrysin derivatives were prepared and evaluated for their inhibitory activities of cyclooxygenase-2 catalyzed prostaglandin production. Chrysin derivatives were prepared from 2-hydroxyacetophenone, 2,4-dihydroxyacetophenone and 2,6-dihydroxyacetophenone in 2 to 4 steps, respectively. Methxoylated chrysin derivatives were converted to the corresponding hydroxylated chrysin derivatives by the reaction with BBr 3 in good yields. The inhibitory activity of the chrysin derivatives against prostaglandin production from lipopolysaccharide-treated RAW 264.7 cells was measured. We found that chrysin derivatives with 3′,4′- dichloro substituents (5e, 6e and 7e) exhibited good inhibitory activity of prostaglandin production.
- Dao, Tran Thanh,Chi, Yeon Sook,Kim, Jeongsoo,Kim, Hyun Pyo,Kim, Sanghee,Park, Haeil
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p. 1165 - 1167
(2007/10/03)
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