The Cu(OTf)<sub>2</sub>- and Yb(OTf)<sub>3</sub>-Catalyzed Claisen Rearrangement of 2-Alkoxycarbonyl-Substituted Allyl Vinyl Ethers
作者:Martin Hiersemann、Lars Abraham
DOI:10.1021/ol006760w
日期:2001.1.1
[figure: see text] The Cu(OTf)2- and Yb(OTf)3-catalyzed Claisen rearrangement of 2-alkoxycarbonyl-substituted allylvinylethers has been developed. Reactivity and stereoselectivity strongly depend on the substrate structure.
Progress in the catalytic asymmetric Claisen rearrangement of 2-alkoxycarbonyl-substituted allyl vinyl ether is reported. Application of a more Lewis acidic catalyst, [Cu(S,S)-t-Bu-box}](H2O)2(SbF6)2, afforded β-chiral α-keto ester with an enantiomeric excess up to 99%. We suggest a highly polarized transition state for the Lewis acid-catalyzed Claisen rearrangement in order to explain the experimental results