Diastereoselective bismuth triflate catalyzed Claisen rearrangement of 2-alkoxycarbonyl-substituted allyl vinyl ethers

Abstract

Listen

Translate article

In the presence of a catalytic amount of bismuth triflate, 2-alkoxycarbonyl-substituted allyl vinyl ethers as a mixture of enol ether double bond isomers were smoothly converted into the β,γ-alkyl-substituted α-keto esters. The isomerization reaction proceeded rapidly to afford smoothly the α-keto esters in good to excellent yields using catalytic amounts of Bi(OTf)3·4H2O (1 mol%). (Z,Z)-2-iso-Propyloxycarbonyl-substituted allyl vinyl ethers 3Z,Z afforded the corresponding β,γ-alkyl-substituted α-keto esters 4 with very good syn diastereoselectivity.Key words: bismuth; bismuth(III) triflate; Claisen rearrangement; allyl vinyl ethers.