Temperature-Controlled Stereodivergent Synthesis of 2,2′-Biflavanones Promoted by Samarium Diiodide |
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Authors: | Martín Soto Dr Raquel G Soengas Prof Artur M S Silva Prof Vicente Gotor-Fernández Prof Humberto Rodríguez-Solla |
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Institution: | 1. Department of Organic and Inorganic Chemistry, University of Oviedo, Avenida Julián Clavería 8, 33006 Oviedo, Spain;2. Research Centre CIAIMBITAL, University of Almería, Carretera de Sacramento s/n, 04120 Almería, Spain;3. Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal |
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Abstract: | 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. |
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Keywords: | flavonoids natural products radical coupling samarium stereodivergent reactions |
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