Base-catalyzed reactions enhanced by solid acids: Amine-catalyzed nitroaldol (Henry) reactions enhanced by silica gel or mesoporous silica SBA-15
作者:Kiyoshi Tanemura、Tsuneo Suzuki
DOI:10.1016/j.tetlet.2017.12.050
日期:2018.1
The reactions of various aldehydes with CH3NO2 catalyzed by Et3N, n-C6H13NH2, and Me2N(CH2)2NH2 were accelerated by the addition of silica gel to givearomatic (aliphatic) β-nitroalcohols, aromatic nitroalkenes, and aromatic 1,3-dinitroalkanes, respectively. Mesoporous silica SBA-15 showed higher activity than silica gel for the synthesis of aromatic nitroalkenes by the reactions of the corresponding
has been used in different non‐conventional biotransformations showing remarkable activity values. The promiscuous behaviour of this enzyme used in the cross‐linked enzyme aggregates immobilized form (Alcalase‐CLEA®), has been successfully demonstrated for the first time in CCbondformation processes such as aldol, Henry and Mannich reactions. On the other hand, the Bayllis–Hillman reaction between
Co‐Polymeric Nanosponges from Cellulose Biomass as Heterogeneous Catalysts for amine‐catalyzed Organic Reactions
作者:Laura Riva、Carlo Punta、Alessandro Sacchetti
DOI:10.1002/cctc.202001157
日期:2020.12.16
nano‐porous system guarantees a complete penetration of CNS, allowingreagents to diffuse within. Indeed, by modulating reaction conditions (catalyst loading, temperature, solvent, microwave versus conventional heating, relative ratio of reagents) it was possible to drive selectivity towards the desired products, while maintaining high efficiency in terms of conversion. The catalyst could be re‐used several
Switchable Perfomance of an <scp>l</scp>-Proline-Derived Basic Catalyst Controlled by Supramolecular Gelation
作者:Francisco Rodríguez-Llansola、Beatriu Escuder、Juan F. Miravet
DOI:10.1021/ja902589f
日期:2009.8.19
catalytic efficiency for the nitroaldol reaction but enhances a reaction pathway leading to alkenes. Because of the reversible nature of supramolecular gels, subtle temperature changes allow for a reversible sol-gel transition associated to an activation of the catalyst. The catalytic gel from nitroethane is significantly more active than the one from nitromethane probably because of its different structure
3-dinitroalkanes. The synthesis proceeds through the nitroaldol reaction of nitromethane, which acts both as nucleophile and as solvent, to the aldehydes with the formation of β-nitroalkanols as intermediates that convert to nitroalkenes. Further nucleophilic behavior of the nitromethane produces the in situ conjugate addition of its carbanion to the formed nitroalkenes giving the one-potsynthesis of the title