16958-22-8Relevant articles and documents
Pd/Al2O3-catalysed redox isomerisation of allyl alcohol: Application in aldol condensation and oxidative heterocyclization reactions
Zsolnai, Dániel,Mayer, Péter,Szori, Kornél,London, Gábor
, p. 3814 - 3820 (2016)
The application of the Pd/Al2O3 catalyst in allyl alcohol isomerization and subsequent aldol condensation and heterocyclization reactions is described. The activity of Pd/Al2O3 in these transformations is suggested to be due to the participation of the Lewis acidic sites of the support in the activation of the alcohol towards oxidative dehydrogenation by the metal and subsequent hydride transfer. The resulting enol(ate)/aldehyde could undergo further reactions promoted by the acid-base properties of the support. In the aldol condensation reactions of the isomerization product, electron poor aromatic aldehydes and heteroaromatic aldehydes showed the highest activity, while aromatic aldehydes bearing electron donating substituents reacted after transformation to the corresponding N-tosyl imines. 1,2-Disubstituted aromatics gave heterocyclic products in one-pot multistep reaction sequences.
Accelerating Amine-Catalyzed Asymmetric Reactions by Intermolecular Cooperative Thiourea/Oxime Hydrogen-Bond Catalysis
Afewerki, Samson,Córdova, Armando,Ibrahem, Ismail,Ma, Guangning,Zhang, Kaiheng
supporting information, p. 3043 - 3049 (2021/07/22)
The ability of intermolecular cooperative thiourea/oxime hydrogen-bond catalysis for improving and accelerating asymmetric aminocatalysis is presented. The two readily available hydrogen-bond-donating catalysts operates in synergy with a chiral amine catalyst to accomplish highly stereoselective transformations. The synergistic catalyst systems simultaneously activate both electrophiles and nucleophiles, and make the transformations more chemo- and stereoselective. This was exemplified by performing co-catalytic enantioselective direct intermolecular α-alkylation reactions of aldehydes, direct aldol reactions, and asymmetric conjugate reactions, which gave the corresponding products in high yields and enantiomeric ratios.
SELF-CONDENSATION OF ALDEHYDES
-
Paragraph 0021; 0027, (2020/06/05)
An efficient process useful for the self-condensation of aliphatic aldehydes is provided, catalyzed by dialkylammonium carboxylate salts. In particular, the invention provides a facile method for the preparation of 2-ethyl hexenal via the self-condensation of butyraldehyde using various dialkylammonium carboxylates, e.g., diisopropylammonium acetate or dimethylammonium acetate, as catalyst. Additionally, residual nitrogen arising from the catalyst can be reduced to -100 ppm levels in the product via a simple washing procedure. The invention provides a process for preparing alkenals under conditions which limit the formation of undesired impurities and high-boiling oligomeric substances.
