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Relevant academic research and scientific papers

Photoinduced electron transfer reactions of flavone with amines -the syntheses of 2,4′- And 2,2′-biflavanoids

Photoinduced electron transfer reactions of flavone (FL) with triethylamine (TEA) in benzene or in acetonitrile gave meso- 2,2′-biflavone 1 and (±)-2,2′-biflavone 2, as well as 2,4′-biflavanoid 3 in good total yield (77% in acetonitrile and 94% in benzene

Temperature-Controlled Stereodivergent Synthesis of 2,2′-Biflavanones Promoted by Samarium Diiodide

In this work, the first example of a radical stereodivergent reaction directed towards the stereoselective synthesis of both (R*,R*)- and (R*,S*)-2,2′-biflavanones promoted by samarium diiodide is reported. Control experiments showed that the selectivity of this reaction was exclusively controlled by the temperature. It was possible to generate a variety of 2,2′-biflavanones bearing different substitution patterns at the aromatic ring in good-to-quantitative yields, being both stereoisomers of the desired compounds obtained with total or high control of selectivity. A mechanism that explains both the generation of the corresponding 2,2′-biflavanones and the selectivity is also discussed. The structure and stereochemistry determination of each isomer was unequivocally elucidated by single-crystal X-ray diffraction experiments.

Photochemical synthesis of 2,2′-biflavanones from flavone

Photolysis of flavone (4) with the electron-donating amines including triethylamine or 2-(N,N-dimethylamino)ethanol in acetonitrile, benzene or methylene dichloride can easily afford two hydrodimers of 2,27prime;-bi- flavanone(racemate) (5a) and 2,2′-biflavanone(meso) (5b) and one reductive product of flavanone (6). Their yields were dependent on the molar ratios of substrate to amine, the kinds of amines, the solvents used and the irradiation sources. Higher yields were afforded 2,27prime;-biflavanone(racemate) (5a), 2,27prime;-biflavanone(meso) (5b) and flavanone (6) (30.0%, 20.9% and 15.8%, respectively) in the reaction condition of 1/2 molar ratio of flavone (4) to triethylamine in acetontrile with fourteen hours of irradiation.

Synthesis of 2,2′-biflavanones from flavone via electrolytic reductive coupling

Flavone (1) was easily reduced by using the electrochemical method to give two hydrodimers of 2,2′-biflavanone(racemate) (5a) and 2,2′-biflavanone(meso) (5b) and one reductive product of flavanone (6). Their yields were dependent on the nature of electrodes, the kinds of supporting electrolytes and the reaction temperature. They were found to afford higher yields of 2,2′-biflavanone(racemate) (5a) and 2,2′-biflavanone (meso) (5b) (32.4% and 24.8%, 35.8% and 13.4%, respectively,) in the reaction conditions of Pb(-)/C(+)-H2SO4-TF/mol and C(-)/C(+)-H 2SO4-5F/mol.

Reaktionen mit Radikalanionen, IV. Synthese von Mono- und Diketonen aus Carboxyl- und α,β-ungesaettigten Carbonyl-Verbindungen

1,2-Diketones of the benzil type were obtained in the reaction of aromatic carboxylic compounds with lithium naphthalenide.The scope of this reaction was investigated. α,β-Unsaturated ketones yielded hydrodimerisation, hydrogenation and hydroxylation products.