1156541-46-6Relevant academic research and scientific papers
A stereoselective and practical synthesis of (E)-α,β-unsaturated ketones from aldehydes
Balducci, Evita,Attolino, Emanuele,Taddei, Maurizio
experimental part, p. 311 - 318 (2011/02/28)
α,β-Unsaturated ketones can be prepared by reaction of differently substituted β-keto acids and aldehydes. The reaction is carried out under organocatalysis (β-alanine, 0.5 equiv.) and generates the enones with high E selectivity (>95%). This version of the Verley-Doebner modification of the Knoevenagel reaction is a practical alternative to the classic Horner-Wadsworth-Emmons (HWE) reaction without the formation of high molecular weight byproducts. The process makes use of simple reagents and can be applied to large-scale synthesis under conditions compatible with atom-economy principles. Differently substituted aliphatic, aromatic, or heteroaromatic α,β-unsaturated ketones can be prepared. An example of a hydroformylation/Verley-Doebner Knoevenagel telescoped process is also described. The conditions used in the Knoevenagel reaction to prepare conjugated esters under amino acid organocatalysis can be applied also for the synthesis of α,β unsaturatedketones. β-Keto acids are prepared byhydrogenolysis of the corresponding benzyl ester and react easily with aldehydes to give the α,β-unsaturated ketones without formation of high molecular weight byproducts. Copyright
Palladium-catalysed heck reactions of alk-1-en-3-ones with aryl bromides: A very simple access to (E)-1-arylalk-1-en-3-ones
Lemhadri, Mhamed,Fall, Yacoub,Doucet, Henri,Santelli, Maurice
experimental part, p. 1021 - 1035 (2009/12/02)
When appropriate reaction conditions are used, very high yields of (E)-1-arylalk-1-en-3-one derivatives can be obtained by palladium-catalysed reactions of alk-1-en-3-ones with aryl bromides. The tetraphosphine cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl) cyclopentane in combination with [Pd(C3H5)Cl]2 was found to be a very efficient catalyst for this reaction. In general, higher reaction rates were observed with electron-poor aryl bromides, but the electron-rich aryl bromides 1-bromo-4-(dimethylamino)benzene and 4-bromoanisole also led to the arylated enones in high yields. Even with sterically very congested aryl bromides such as 9-bromoanthracene, 1-bromo-2,4,6-trimethylbenzene or 1-bromo-2,4,6-triisopropylbenzene, the expected (E)-1-arylalk-1-en-3-ones were obtained in moderate to good yields. These enones appear to be unstable under the reaction conditions, and the addition of a small amount of hydroquinone to the reaction mixture was found to be crucial, especially for the vinylation of electron-deficient aryl bromides. A variety of alk-1-en-3-ones has been employed, and better results in terms of substrate/ catalyst ratios were obtained when oct-1-en-3-one or hex-1-en-3-one was used than when but-1-en-3-one or pent-1-en-3-one was used. It should be noted that several reactions can be performed with as little as 0.1-0.001 mol% catalyst. Georg Thieme Verlag Stuttgart.
