Herein, we report a synthetic method with improved selectivity for 5-substituted flavonols via the Algar-Flynn-Oyamada reaction (AFO), by using of sodium carbonate/hydrogen peroxide A series of 5-substituted flavonols was obtained with moderate to high yields. The mechanism of the AFO reaction was elucidated. LCMS analysis and in situ 1H NMR analysis indicated that the epoxide was involved in the transformation from chalcone to flavonol and/or aurone under alkaline base/peroxide conditions.An efficient method for synthesis of 5-substituted flavonol was provided. The mechanism of Algar-Flynn-Oyamada reaction (AFO) was elucidated by LCMS study and in situ NMR analysis.Download high-res image (205KB)Download full-size image

Mesoporous silicates functionalized with amino groups in the pore channels have been made by the co-condensation of tetraethoxyl siloxide (TEOS) with precursors of P–Si through a triblock copolymer-templated sol–gel process under acidic conditions. Poly(alkylene oxide) block copolymer (P123) was eluted by ethanol extraction and template molecules were removed by refluxing the materials in a mixture of DMSO and water. The resulting materials were characterized in detail by FT-IR, XRD, TEM and N2 adsorption, in order to study the effect of the precursors on the mesoscopic order and pore structure. Evidence of amino groups located in the pore channels was shown through variation of pore size and BET surface area after the amino groups were coupled with benzaldehyde, and TEM images of materials after staining with RuO4. Finally, a comparative study of the catalytic performance of materials SBA-Am-10 and SBA-T-10, obtained by two methods, revealed that the catalyst synthesized by our method gave rapid reaction speed and high yields of flavanone by the Claisen–Schmidt condensation of benzaldehyde and 2′-hydroxyacetophenone.

Various 4H-benzo[b]pyran derivatives were synthesized via a one-pot three-component condensation of arylaldehyde, malononitrile and dimedone in water using β-cyclodextrin (β-CD) as an efficient catalyst. This method provides several advantages, including mild reaction conditions, operational simplicity, high yields and minimal pollution of the environment.

A copper-mediated Duff reaction for ortho-selective formylation of phenols has been developed. In the presence of copper species, significant improvements of yield and ortho-selectivity of the Duff formylation were achieved, which provides an easy access to salicylaldehydes from phenols.

A copper-catalyzed decarboxylative intramolecular C–O coupling reaction was established. Under aerobic conditions in the presence of cupric chloride/1,10-phenathroline, a variety of 2-arylbenzofurans were prepared from 3-arylcoumarins in one-pot with yields from 26% to 84%.

Hantzsch 1,4-dihydropyridines were converted to the corresponding pyridines efficiently by sodium chlorite under mild conditions in excellent yields.