6963-39-9Relevant articles and documents
Multi-Photocatalyst Cascades: Merging Singlet Oxygen Photooxygenations with Photoredox Catalysis for the Synthesis of Alkaloid Frameworks
Kalaitzakis, Dimitris,Bosveli, Artemis,Sfakianaki, Kalliopi,Montagnon, Tamsyn,Vassilikogiannakis, Georgios
supporting information, p. 4335 - 4341 (2020/12/18)
The development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic alkaloid frameworks or erythrina natural products is described. Each of the sequences developed makes use of photocatalyzed energy transfer processes, which generate singlet oxygen, to set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon-centered radicals for the cyclizations that give the final complex frameworks. A chemical switch has been developed that can “switch off” one photocatalyst; thus, allowing a second photocatalyst to take over control of the sequence. As a corollary, this strategy represents the first time it has been possible to use multiple photocatalysts in photocascades, and, as such, it expands significantly the reactions that can be included in such cascades and the order in which they can be initiated.
Zeolite-Encapsulated Pt Nanoparticles for Tandem Catalysis
Cho, Hong Je,Kim, Doyoung,Li, Jing,Su, Dong,Xu, Bingjun
supporting information, p. 13514 - 13520 (2018/10/20)
Encapsulation of metal nanoparticles in a zeolite matrix is a promising route to integrate multiple sequential reactions into a one-pot and one-step tandem catalytic reaction. We report a cationic polymer-assisted synthetic strategy to encapsulate Pt nanoparticles (NPs) into MFI zeolites. Degrees of encapsulation of Pt NPs in the synthesized catalysts exceeding 90% were demonstrated via kinetic studies of model reactions involving substrates with different molecular dimensions. HZSM-5 zeolite-encapsulated Pt NPs are able to selectively mediate the tandem aldol condensation and hydrogenation of furfural and acetone to form hydrogenated C8 products with a combined yield of 87%. In contrast, hydrogenation and decarbonylation of furfural dominate on Pt NPs supported on HZSM-5 at otherwise identical conditions. The high selectivity toward the tandem reaction on the encapsulated catalyst is attributed to the distribution of metal and acid sites, which limits the access of furfural to Pt sites and promotes the acid-catalyzed aldol condensation. This is the first demonstration that the product distribution in a tandem reaction is manipulated by tailoring the architecture of catalytic materials via encapsulation.
Enhancing the Catalytic Properties of Ruthenium Nanoparticle-SILP Catalysts by Dilution with Iron
Luska, Kylie L.,Bordet, Alexis,Tricard, Simon,Sinev, Ilya,Grünert, Wolfgang,Chaudret, Bruno,Leitner, Walter
, p. 3719 - 3726 (2016/07/06)
The partial replacement of ruthenium by iron ("dilution") provided enhanced catalytic activities and selectivities for bimetallic iron-ruthenium nanoparticles immobilized on a supported ionic liquid phase (FeRuNPs@SILP). An organometallic synthetic approach to the preparation of FeRuNPs@SILP allowed for a controlled and flexible incorporation of Fe into bimetallic FeRu NPs. The hydrogenation of substituted aromatic substrates using bimetallic FeRuNPs@SILP showed high catalytic activities and selectivities for the reduction of a variety of unsaturated moieties without saturation of the aromatic ring. The formation of a bimetallic phase not only leads to an enhanced differentiation of the hydrogenation selectivity, but even reversed the order of functional group hydrogenation in certain cases. In particular, bimetallic FeRuNPs@SILP (Fe:Ru = 25:75) were found to exhibit accelerated reaction rates for C=O hydrogenation within furan-based substrates which were >4 times faster than monometallic RuNPs@SILP. Thus, the controlled incorporation of the non-noble metal into the bimetallic phase provided novel catalytic properties that could not be obtained using either of the monometallic catalysts.
