Highly enantioselective catalytic asymmetric Claisen rearrangement of 2-alkoxycarbonyl-substituted allyl vinyl ethers

Abstract

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}](H 2O) 2(SbF 6) 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.