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  • Title: Asymmetric tandem conjugate addition-protonation to forge chiral secondary C-O bonds for quaternary carbon stereocenters at the nonadjacent β-position.
    Author: Hong SN, Liu Y, Lee R, Jiang Z.
    Journal: Chem Commun (Camb); 2017 Jul 04; 53(54):7493-7496. PubMed ID: 28627560.
    Abstract:
    A direct strategy to construct chiral secondary C-O bonds for quaternary carbon stereocenters at the nonadjacent β-position is described. Methylene 1,3-oxazolidine-2,4-diones were for the first time employed in an asymmetric reaction as viable electrophiles undergoing a tandem conjugate addition-protonation process. Using an l-amino acid-based urea-tertiary amine catalyst, the reaction with 3-substituted oxindoles gave valuable protonation adducts featuring 1,3-quaternary-tertiary (C-O) nonadjacent stereocenters in high yields and excellent stereoselectivities. The method was successfully extended to sulphur nucleophiles for synthesizing chiral 1,3-sulfur-tertiary alcohol derivatives with bioactive importance.
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