Switchable Diastereoselectivity in the Fluoride Promoted Vinylogous Mukaiyama-Michael Reaction of 2-Trimethylsilyloxyfuran Catalyzed by Crown Ethers

Giorgio Della Sala, Marina Sicignano, Rosaria Schettini, Francesco De Riccardis, Luigi Cavallo, Yury Minenkov, Chloé Batisse, Gilles Hanquet, Frederic Leroux, Irene IZZO

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7 Scopus citations

Abstract

The fluoride promoted vinylogous Mukaiyama-Michael reaction (VMMR) of 2-trimethylsilyloxyfuran with diverse α,β-unsaturated ketones is described. The TBAF catalyzed VMMR afforded high anti-diastereoselectivity irrespective of the solvents used. The KF/crown ethers catalytic systems proved to be highly efficient in terms of yields and resulted in a highly diastereoselective unprecedented solvent/catalyst switchable reaction. Anti-adducts were obtained as single diastereomers or with excellent diastereoselectivities when benzo-15-crown-5 in CH2Cl2 was employed. On the other hand, high syn-diastereoselectivities (from 76:24 to 96:4) were achieved by employing dicyclohexane-18-crown-6 in toluene. Based on DFT calculations, the catalysts/solvents-dependent switchable diastereoselectivities are proposed to be the result of loose or tight cation-dienolate ion pairs.
Original languageEnglish (US)
Pages (from-to)6629-6637
Number of pages9
JournalThe Journal of Organic Chemistry
Volume82
Issue number13
DOIs
StatePublished - Jun 13 2017

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