18618-91-2Relevant articles and documents
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Casnati,G. et al.
, p. 959 - 962 (1974)
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Metal-Organic Frameworks Invert Molecular Reactivity: Lewis Acidic Phosphonium Zwitterions Catalyze the Aldol-Tishchenko Reaction
Bauer, Gerald,Ongari, Daniele,Xu, Xiaoying,Tiana, Davide,Smit, Berend,Ranocchiari, Marco
supporting information, p. 18166 - 18169 (2017/12/27)
The influence of metal-organic frameworks (MOFs) as additives is herein described for the reaction of n-alkyl aldehydes in the presence of methylvinylketone and triphenylphosphine. In the absence of a MOF, the expected Morita-Baylis-Hillman product, a β-hydroxy enone, is observed. In the presence of MOFs with UMCM-1 and MOF-5 topologies, the reaction is selective to Aldol-Tishchenko products, the 1 and 3 n-alkylesters of 2-alkyl-1,3-diols, which is unprecedented in organocatalysis. The (3-oxo-2-butenyl)triphenylphosphonium zwitterion, a commonly known nucleophile, is identified as the catalytic active species. This zwitterion favors nucleophilic character in solution, whereas once confined within the framework, it becomes an electrophile yielding Aldol-Tishchenko selectivity. Computational investigations reveal a structural change in the phosphonium moiety induced by the steric confinement of the framework that makes it accessible and an electrophile.
Lithium Tungsten Dioxide Promoted Claisen-Tishchenko Condensation of Aromatic and Aliphatic Aldehydes
Villacorta, Gilberto M.,Filippo, Joseph San
, p. 1151 - 1154 (2007/10/02)
Lithium tungsten dioxide, LiWO2, has been shown to be a useful catalyst for effecting the Claisen-Tishchenko condensation of aldehydes under heterogeneous conditions.
