Synthesis, resolution and applications of 3,3′-bis(RO)-MeO-BIPHEP derivatives |
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Authors: | Evgueni Gorobets |
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Institution: | Department of Chemistry, University of Calgary, Calgary, Alta, Canada T2N 1N4 |
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Abstract: | A series of optically pure 3,3′-bis(RO)-MeO-BIPHEP derivatives are prepared and used in palladium catalyzed asymmetric transformations. The phosphine oxide of (±)-5 is prepared in four steps from p-methoxyphenol and resolved using the novel resolving reagent chloro(l-menthoxy)dimethylsilane. Subsequent conversions provide catalysts 8 and 9. Ligands 6, 7 and 10 are prepared in six steps from p-methoxyphenol and the phosphine oxides of 6 and 7, and 10 are resolved using di-p-toluoyl- and dibenzoyl-l-tartaric acid, respectively. (R)-3,3′-Bispivalate 8 is superior to the other catalysts in asymmetric Heck reaction with 2,3-dihydrofuran while (R)-(+)-bis(tolyloxy) 10 and (+)-(R)-sugar derivative 9 are better in the Pd-catalyzed polyene cyclization; however, the absolute sense of chirality in the product from the polyene cyclization was reversed to that obtained when (R)-(+)-BINAP and (R)-(+)-MeO-BIPHEP were used. |
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Keywords: | Asymmetric Heck Asymmetric polyene cyclizations Palladium 3 3&prime -Disubstituted BIPHEP derivatives |
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