| 概要 |
p-Block elements alone or assisted by transition metal catalysts have the ability to lower the activation energy towards enabling novel chemical reactions that would not be achievable otherwise. This is best exemplified by cutting-edge innovations in transition metal (nano)catalysis exploiting metal-metal interactions rely on precluding agglomeration pathways leading to catalyst passivation via bulk metal formation. [1] This talk will be divided into two main axes in order to overview both molecular strategies as well as surface-catalyzed transformations using tailored nanoparticle systems with high specific surface areas. With a special emphasis on catalyst design, this presentation will provide an overview on C–C and C–heteroatom couplings and multicomponent metal‐catalyzed reactions with a special emphasis on the selective transformation of C–H bonds via novel strategies comprising both molecular complexes and metal-based nanoparticles with enhanced surface reactivity, thus harnessing sustainable processes. An account of our work focusing on bottom-up strategies for the synthesis of both mono- (Pd, Pt, Ru, Cu, Ni, Co) and bi- metallic nanoparticles (Ni/Co, Pd/Cu) metal-based nanoparticles immobilized both in liquid media (glycerol, biosourced ionic liquids) [2] as well as on inorganic supports (hydrochars, halloysite, hydroxyapatite, TiO 2 , MgAl 2 O 4 ) [3] will be presented with a special emphasis on the metal precursors and the nature of stabilizers (such as amines, ammonium salts, phosphines and biomass-based alkaloids). A combination of techniques has been used for the full characterization of the as-prepared catalytic materials (PXRD, X-ray fluorescence, XPS, XAS, (HR)TEM, FTIR, ssNMR, EPR, magnetization…), as well as to assess their catalytic behavior towards a number of chemical transformations. Efficient catalytic applications by means of C–C homocoupling [4] and (de)hydrogenation reactions together with mechanistic insights will be presented. [5] Moreover, straightforward and atom economical catalytic methods to effect multicomponent reactions via molecular processes streamlining the synthesis of nitrogen-containing heterocycles such as oxazolidinones, and imidazo[1,5- a]pyridines [6] will also be presented using Cu catalysis. Nevertheless, the development of chemical processes to embed main group elements encompasses huge potential towards the development of functional compounds and materials such as molecular switches, frustrated Lewis pairs [7] and trifluoroborate-based probes that can be used as prosthetic groups for [ 18 F]fluorination via F-18 for F-19 isotopic exchange (IEX) in water. [8] Finally, a sequential process combining both multi-component reactions towards the upgrading of green-house gases into amines via a dual catalytic strategy will be presented, namely i) the tri-reforming of methane (TRM) [9] catalyzed by supported Ni-based nanocatalysts for the production of syngas and ii) the hydroaminomethylation (HAM) for the synthesis of homologated terpenic amines from syngas and terpenes, catalyzed by Rh-Co molecular complexes (Figure 1), with an special emphasis on catalyst loading, choice of metal pre-catalysts and ligands/stabilizers, optimization of operating conditions in the quest for efficient catalysts. This original bimetallic catalytic system based on Rh(I) and Co(0) in glycerol afforded the synthesis of terpenic amines taking advantage of cooperative effects. [10] These results represent attractive means to expand the exploration of chemical space through novel synthetic tools to override the dependence on fossil resources.
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Summary |
