90784-76-2Relevant academic research and scientific papers
Synthesis of α-substituted γ,δ-unsatured β-oxo esters
Goorbergh, J. A. M. van den,Gen, A. van der
, p. 90 - 96 (2007/10/02)
Two approaches to the synthesis of the title compounds 3 are described.The first consist of direct alkylation of the unsatured β-oxo esters 1 via their monoanions.The best results were obtained using the heterogeneous sodium methoxide/alumina system.Isolation of pure, mono-α-alkylated compounds requires chromatographic separation of the reaction products.The second approach makes use of the Horner-Wittig reaction. α-substituted phosphine oxides 4 were converted into their dianions and reacted with aldehydes and ketones to afford the mono-α-alkylated β-oxo esters 3 in good yields.The requisite phosphine oxides were obtained from the corresponding γ-bromo β-oxo esters 10 via an Arbusov reaction with ethyl diphenylphosphinite.Finally, it was found that α,α-dialkylated and α,α,γ-trialkylated β-oxo esters 8 and 15 can be obtained by reaction of 1 with an excess of alkyl halide in the presence of two or four equivalents of sodium hydride, respectively.
