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Asymmetric tandem conjugate addition–protonation to forge chiral secondary C–O bonds for quaternary carbon stereocenters at the nonadjacent β-position†
San-Ni Hong,Yang Liu,Richmond Lee,Zhiyong Jiang
Chemical Communications Pub Date : 06/13/2017 00:00:00 , DOI:10.1039/C7CC03700G
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.

Graphical abstract: Asymmetric tandem conjugate addition–protonation to forge chiral secondary C–O bonds for quaternary carbon stereocenters at the nonadjacent β-position
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