840475-21-0Relevant articles and documents
Thermal effects in the organocatalytic asymmetric Mannich reaction
Rodriquez, Belen,Bolm, Carsten
, p. 2888 - 2891 (2006)
The proline-catalyzed direct asymmetric Mannich reaction between cyclohexanone, formaldehyde, and various anilines is thermally accelerated. With only 0.5 mol % of catalyst, Mannich products with up to 98% ee have been obtained after a short period of tim
Inductive heating with magnetic materials inside flow reactors
Ceylan, Sascha,Coutable, Ludovic,Wegner, Jens,Kirschning, Andreas
supporting information; experimental part, p. 1884 - 1893 (2011/03/21)
Superparamagnetic nanoparticles coated with silica gel or alternatively steel beads are new fixed-bed materials for flow reactors that efficiently heat reaction mixtures in an inductive field under flow conditions. The scope and limitations of these novel heating materials are investigated in comparison with conventional and microwave heating. The results suggest that inductive heating can be compared to microwave heating with respect to rate acceleration. It is also demonstrated that a very large diversity of different reactions can be performed under flow conditions by using inductively heated flow reactors. These include transfer hydrogenations, heterocyclic condensations, pericyclic reactions, organometallic reactions, multicomponent reactions, reductive cyclizations, homogeneous and heterogeneous transition-metal catalysis. Silica-coated iron oxide nanoparticles are stable under many chemical conditions and the silica shell could be utilized for further functionalization with Pd nanoparticles, rendering catalytically active heatable iron oxide particles.
Tosylhydrazide-promoted palladium-catalyzed reaction of β-aminoketones with o-dihaloarenes: Combining organocatalysis and transition-metal catalysis
Barluenga, Jose,Quinones, Noelia,Cabal, Maria-Paz,Aznar, Fernando,Valdes, Carlos
supporting information; experimental part, p. 2350 - 2353 (2011/04/21)
(Chemical Equation Presented) Working in tandem: Mannich adducts obtained by organocatalyzed processes are readily transformed into phenanthridine and quinoline derivatives by a Pd-catalyzed cascade reaction involving tosylhydrazide (TsNHNH2)-promoted cross-coupling followed by intramolecular amination (see scheme; MW=microwave). The enantioselectivity achieved in the organocatalytic reaction is maintained throughout the process.
Microwave-assisted asymmetric organocatalysis. A probe for nonthermal microwave effects and the concept of simultaneous cooling
Hosseini, Masood,Stiasni, Nikola,Barbieri, Vera,Kappe, C. Oliver
, p. 1417 - 1424 (2007/10/03)
(Chemical Equation Presented) A series of five known asymmetric organocatalytic reactions was re-evaluated at elevated temperatures applying both microwave dielectric heating and conventional thermal heating in order to probe the existence of specific or nonthermal microwave effects. All transformations were conducted in a dedicated reactor setup that allowed accurate internal reaction temperature measurements using fiber-optic probes. In addition, the concept of simultaneous external cooling while irradiating with microwave power was also applied in all of the studied cases. This method allows a higher level of microwave power to be administered to the reaction mixture and, therefore, enhances any potential microwave effects while continuously removing heat. For all of the five studied (S)-proline-catalyzed asymmetric Mannich- and aldol-type reactions, the observed rate enhancements were a consequence of the increased temperatures attained by microwave dielectric heating and were not related to the presence of the microwave field. In all cases, in contrast to previous literature reports, the results obtained either with microwave irradiation or with microwave irradiation with simultaneous cooling could be reproduced by conventional heating at the same reaction temperature and time in an oil bath. No evidence for specific or nonthermal microwave effects was obtained.
Direct organocatalytic enantioselective α-aminomethylation of ketones
Ibrahem, Ismail,Zou, Weibiao,Casas, Jesús,Sundén, Henrik,Córdova, Armando
, p. 357 - 364 (2007/10/03)
The scope and limitations of the direct organocatalytic asymmetric α-aminomethylation of ketones are disclosed. The proline-catalyzed classical Mannich reactions between unmodified ketones, aqueous formaldehyde and aromatic amines furnished the desired Ma
