Cerium oxide as a catalyst for the ketonization of aldehydes: mechanistic insights and a convenient way to alkanes without the consumption of external hydrogen
Lanthanoid triisopropoxides are active catalysts for aldol reactions. Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures. Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields. The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation. In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide. Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
A green method for the self-aldol condensation of aldehydes using lysine
作者:Yutaka Watanabe、Kazue Sawada、Minoru Hayashi
DOI:10.1039/b918349c
日期:——
A self-condensation of aldehydes has been conveniently accomplished by the catalytic action of lysine in water or a solvent-free system under specific emulsion conditions to give α-branched α,β-unsaturated aldehydes in good yields.
Synthesis of Guerbet ionic liquids and extractants as β-branched biosourceable hydrophobes
作者:Giacomo Damilano、Koen Binnemans、Wim Dehaen
DOI:10.1039/c9ob02237f
日期:——
amines and β-branched quaternaryammonium chloride ionic liquids as novel extractants. The synthesis methodology was tailored to facilitate the reaction scale-up and the use of biorenewable starting materials. The developed process is an overall green, easy and straightforward synthesis of β-branched amines, and ammoniumsalts, starting from linear aldehydes. In order to evaluate the potential of the