A general stereoselective method for the synthesis of cyclopropanecarboxylates. A new version of the homologous Horner–Wadsworth–Emmons reaction
作者:Henryk Krawczyk、Katarzyna Wąsek、Jacek Kędzia、Jakub Wojciechowski、Wojciech M. Wolf
DOI:10.1039/b712145h
日期:——
The synthesis of α-, β- and γ-substituted α-phosphono-γ-lactones was accomplished using different ring closure and ring homologation strategies. It was found that the lactones could be selectively transformed into the corresponding ethyl cyclopropanecarboxylates by treatment with sodium ethoxide in boiling THF. The reported reaction provides an attractive alternative to the classical homologous HornerâWadsworthâEmmons approach to the construction of cyclopropanes with electron-withdrawing functionalities.
The intramolecular Wittig–Horner reaction of α-diethoxyphosphinyl-Δα,β-butenolides with various nucleophilic reagents containing the carbonyl group produced α,β-carbocyclic fused-γ-lactones in moderate yields.
Synthesis of substituted 3-furan-2(5H)-ones via an anthracene Diels–Alder sequence
作者:Simon Jones、Ian Wilson
DOI:10.1016/j.tetlet.2006.04.097
日期:2006.6
Deprotonation then electrophilic quench of the lactone derived from the Diels–Alder addition adduct of anthracene and maleicanhydride gave α-substituted lactones in good yield. Of particular note was the reaction with chlorotrimethylsilane which gave only the C-silylated product. Flash vacuum pyrolysis (FVP) of the alkylated products afforded 3-substituted furan-2(5H)-ones in good overall yield.