- Site- And enantiodifferentiating C(sp3)-H oxidation enables asymmetric access to structurally and stereochemically diverse saturated cyclic ethers
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A manganese-catalyzed site- and enantiodifferentiating oxidation of C(sp3)-H bonds in saturated cyclic ethers has been described. The mild and practical method is applicable to a range of tetrahydrofurans, tetrahydropyrans, and medium-sized cyclic ethers with multiple stereocenters and diverse substituent patterns in high efficiency with extremely efficient site- and enantiodiscrimination. Late-stage application in complex biological active molecules was further demonstrated. Mechanistic studies by combined experiments and computations elucidated the reaction mechanism and origins of stereoselectivity. The ability to employ ether substrates as the limiting reagent, together with a broad substrate scope, and a high level of chiral recognition, represent a valuable demonstration of the utility of asymmetric C(sp3)-H oxidation in complex molecule synthesis.
- Liu, Lei,Sun, Shutao,Yang, Yiying,Zhang, Dongju,Zhao, Ran
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p. 19346 - 19353
(2020/12/01)
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- Palladium-catalyzed asymmetric synthesis of 2-alkynyl oxacycles
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Oxyacetylene: Unusual palladium-catalyzed cyclizations of cyclic and acyclic propargylic carbonates give 2-alkynyl oxacycles. The reactions proceed with very high stereoselectivity for both syn- and anti-disubstituted furans and pyrans, and with exceptional regioselectivity. In addition, two-directional cyclizations of bis-propargylic carbonate substrates yield bifurans with complete stereocontrol for all diastereomers.
- Daniels, David S. B.,Thompson, Amber L.,Anderson, Edward A.
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p. 11506 - 11510
(2012/01/11)
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