Reusable Copper Catechol‐based Porous Polymers for the Highly Efficient Heterogeneous Catalytic Oxidation of Secondary Alcohols

New catechol-based porous polymers were synthesized and used as platforms for the heterogenization of molecular Cu complexes. The resulting Cu@CatMP-1 materials proved to be highly stable and performing catalysts for the oxidation of secondary alcohols with turnover numbers up to 6000, about 1 to 2 orders of magnitude higher than the current relevant state of the art, using catalyst loadings as low as 25 ppm of Cu. The solid catalyst proved to be recyclable for over 10 runs without detectable metal leaching and has been scaled to the gram scale. The coordination of Cu to catechol within the polymer has been evidenced by X-ray absorption spectroscopy

De catalyseurs moléculaires jusqu'à leur incorporation dans des matériaux poreux : le cas de l'arylation CH aromatique régiospécifique

Les motifs hétérobiaryls sont des motifs omniprésents dans les ingrédients pharmaceutiques actifs des médicaments commercialisés et dans les matériaux ayant des applications optoélectroniques. L'arylation directe des liaisons aromatiques C-H a déjà fait ses preuves car elle a permis la construction de ces molécules complexes. L'hétérogénéisation de catalyseurs moléculaires actifs pour l'arylation CH dans les macroligands peut être considérée comme une stratégie pour empêcher la désactivation de systèmes moléculaires bien définis. Un aperçu général sur l'arylation CH ainsi que sur les macroligands poreux pour l'hétérogénéisation est donné au chapitre 1. Au chapitre 2, l'hétérogénéisation des catalyseurs moléculaires au sein des macroligands poreux est présentée. Deux types différents de matériaux poreux, MOF et POP, sont synthétisés et caractérisés. Ils servent de plates-formes pour l'hétérogénéisation des catalyseurs de métaux de transition moléculaire à base de Pd et Ni. Dans le chapitre 3, une nouvelle réaction est développée traitant de l'arylation directe catalysée par le palladium de l'indole en position C3. Après une enquête détaillée de la réaction, un mécanisme complet est présenté. De plus, des essaies d'hétérogénéisation du nouveau protocole homogène sont présentés. Dans le chapitre 4, une autre nouvelle réaction est développée qui démontre l'arylation directe du benzothiophène en position C2 catalysée par le nickel et des composés hétéroaromatiques apparentés. Des investigations mécanistes conduisent à la formulation d'un postulat de mécanisme. Enfin, l'hétérogénéisation de cette réaction ainsi qu'un recyclage répété du catalyseur sont présentés. Le chapitre 5 propose ensuite des conclusions et perspectives critiques de ce travail et la partie expérimentale se trouve au chapitre 6Heterobiaryl patterns are a ubiquitous motifs in active pharmaceutical ingredients of marketed drugs and in materials with optoelectronic applications. The direct arylation of aromatic C-H bonds has already proven its power as it has permitted the construction of these complex molecules. The heterogenization of active molecular catalysts for CH arylation within macroligands can be seen as a strategy to prevent deactivation of well-defined molecular systems. A general overview on CH arylation as well as porous macroligands for heterogenization is given in chapter 1. In chapter 2, the heterogenization of molecular catalysts within porous macroligands is presented. Two different types of porous materials, MOF and POP, are synthesized and characterized. They serve as platforms for the heterogenization of molecular transition metal catalysts based on Pd and Ni. In chapter 3, a novel reaction is developed dealing with the palladium catalyzed direct C3 arylation of indole. After a detailed investigation of the reaction, a comprehensive mechanism is presented. Further, attempts for the heterogenization of the new homogeneous protocol are shown. In chapter 4 another novel reaction is developed that demonstrates the nickel catalyzed direct C2 arylation of benzothiophene and related compounds. Mechanistic investigations lead to the formulation of a mechanism postulate. Finally, the heterogenization of this reaction along with a repeated recycling of the catalyst is presented. Chapter 5 then offers critical conclusions and perspectives of this work and the experimental part can be found in chapter

Regiospecificity in Ligand-Free Pd-Catalyzed C–H Arylation of Indoles: LiHMDS as Base and Transient Directing Group

International audienceA highly efficient catalyst-base pair for the C-H arylation of free (NH)-indoles in the C-3 position is reported. Ligand-free palladium acetate coupled with lithium hexamethyldisilazide (LiHMDS) catalyzed the regiospecific, i.e. 100% regioselective, C-3 arylation of indoles with high turnover numbers. This catalytic system has been successfully applied to a wide range of substrates including various functional aryl halides and indolic cores. The unique role of LiHMDS as both a base and unexpected transient directing group has been revealed experimentally and elucidated computationally, in line with a Heck-type insertion-elimination mechanism

Heterogenization of a Molecular Ni Catalyst within a Porous Macroligand for the Direct C-H Arylation of Heteroarenes

International audienceDirect C–H functionalization catalyzed by a robust and recyclable heterogeneous catalyst is highly desirable for sustainable fine chemical synthesis. Bipyridine units covalently incorporated into the backbone of a porous organic polymer were used as a porous macroligand for the heterogenization of a molecular nickel catalyst. A controlled nickel loading within the porous macroligand is achieved, and the nickel coordination to the bipyridine (bpy) sites is assessed at the molecular level using IR and solid-state NMR spectroscopy. The heterogenized Ni-bpy catalyst was successfully applied to the direct and fully selective C2 arylation of benzothiophenes, thiophene, and selenophene, as well as for the arylation of free NH-indole. Recyclability of the catalyst was achieved by employing hydride activators to reach a cumulative turnover number of more than 300 after seven cycles of catalysis, which corresponds to a total productivity of 12 g of 2-phenylbenzothiophene, chosen as model target biaryl, per gram of catalyst

Hammett Parameter in Microporous Solids as Macroligands for Heterogenized Photocatalysts

Here we present a series of heterogeneous catalysts based on metal–organic frameworks and microporous polymers used as macroligands for heterogenized organometallic complexes. We show that both homogeneous and heterogenized catalysts follow the same linear correlation between the electronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. This correlation highlights the crucial impact of the local electronic environment surrounding the active catalytic center over the long-range framework structure of the porous support. The rational design of heterogenized catalysts can thus be guided by molecular chemistry rules. The conception of highly efficient heterogeneous catalyst based on porous polymer support and driven by the Hammett parameter of bipyridine-chelating macroligand is demonstrated here for the Rh-catalyzed photoreduction of carbon dioxide with turnover frequencies up to 28 h^–1, among the highest reported for heterogeneous photocatalytic formate production

Molecular Porous Photosystems Tailored for Long-Term Photocatalytic CO2 Reduction

RMN+ECI2D:ING+FWI:AGH:YMO:CLO:DFA:JECInternational audienceHerein, we report the molecular-level structuration of two full photosystems into conjugated porous organic polymers. The strategy of heterogenization gives rise to photosystems which are still fully active after 4 days of continuous illumination. Those materials catalyse the carbon dioxide photoreduction driven by visible light to produce up to three grams of formate per gram of catalyst. The covalent tethering of the two active sites into a singleframework is shown to play a key role in the visible light activation of the catalyst. The unprecedented long-term efficiency arises from an optimal photoinduced electron transfer from the light harvesting moiety to the catalytic site as anticipated by quantum mechanical calculations and evidenced by in-situ ultrafast time-resolved spectroscopy