The Pd(II)-Catalyzed and the Thermal Claisen Rearrangement of 2-Alkoxycarbonyl-Substituted Allyl Vinyl Ethers
作者:Martin Hiersemann
DOI:10.1055/s-1999-2932
日期:1999.11
Heating the 2-alkoxycarbonyl-substituted allyl vinyl ethers 2a-c as a mixture of enol ether double bond isomers in the presence of 5 mol% Pd2Cl2(PhCN)2 afforded the β,γ-alkyl-substituted α-keto esters 3a-c as an anti:syn >9 : 1 mixture of diastereomers. (E,E)-2a-c rearranges Pd(II)-catalyzed via a boatlike transition state whereas (Z,E)-2a-c undergoes the thermal rearrangement via a chairlike transition state.
在 5 mol% Pd2Cl2(PhCN)2 存在下,加热 2-烷氧基羰基取代的烯丙基乙烯基醚 2a-c 作为烯醇醚双键异构体的混合物,可得到δ,δ-烷基取代的δ-酮酯 3a-c 作为非对映异构体的反:同>9:1 混合物。(E,E)-2a-c在钯(II)催化下通过舟状转变态进行重排,而(Z,E)-2a-c则通过椅状转变态进行热重排。