Cross-linked polystyrene-TiCl4 complex as a reusable Lewis acid catalyst for solvent-free Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes
作者:Ali Rahmatpour、Niloofar Goodarzi
DOI:10.1016/j.catcom.2018.11.001
日期:2019.5
in the range of (50–80 mesh size) were prepared by a new method, characterized and functionalized with titaniumtetrachloride to afford the corresponding polystyrene‑titaniumtetrachloridecomplex in one step reaction and characterized by FT-IR, UV, TGA, DSC, XRD, SEM, BET. This polymer metal complex (PS/TiCl4) was used as a heterogeneous, recoverable, reusable Lewis acid for solvent-free Knoevenagel
utilized as an efficient heterogeneous recyclable catalyst for Knoevenagel condensationbetween poorly reactive β-diketones and aldehydes under solvent-free conditions. This protocol also works well with more reactive β-ketoesters. The condensation is efficient, clean, and mild. The scope and generality of the Knoevenagel condensation were investigated. The procedure led only to the Knoevenagel product,
Enzyme Promiscuity as a Remedy for the Common Problems with Knoevenagel Condensation
作者:Dominik Koszelewski、Ryszard Ostaszewski
DOI:10.1002/chem.201901491
日期:2019.8
lipase‐catalyzed tandemreaction toward α,β‐enones/enoesters is presented. For the synthesis of the desired products the tandem process based on enzyme‐catalyzed hydrolysis and Knoevenagel reaction starting from enol acetates and aldehyde is developed. The relevant impact of the reaction conditions including organic solvent, enzyme type, and temperature on the course of the reaction was revealed. It
A new protocol for the Knoevenagel condensation between β-diketones and aliphatic and aromatic aldehydes promoted by Mg(ClO4)2 under mild conditions is reported.
Enzyme catalytic promiscuity: The papain-catalyzed Knoevenagel reaction
作者:Wen Hu、Zhi Guan、Xiang Deng、Yan-Hong He
DOI:10.1016/j.biochi.2011.09.018
日期:2012.3
Knoevenagel reactions in DMSO/water. A wide range of aromatic, hetero-aromatic and α,β-unsaturated aldehydes could react with less active methylene compounds acetylacetone and ethyl acetoacetate. The products were obtained in moderate to excellent yields with Z/E selectivities of up to 100:0. This case of biocatalytic promiscuity not only widens the application of papain to new chemical transformations