Enantioselective Heterogeneous Synergistic Catalysis for Asymmetric Cascade Transformations

Deiana, Luca; Ghisu, Lorenza; Afewerki, Samson; Verho, Oscar; Johnston, Eric V.; Hedin, Niklas; Bacsik, Zoltán; Córdova, Armando

doi:10.1002/adsc.201400291

Cited by 55 publications

(21 citation statements)

References 80 publications

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“…Concerted catalysis between metal complexes and organic functional groups is a notable strategy to create novel heterogeneous catalysis and a highly efficient technique for molecular transformations . Several research groups have reported Pd, Rh, and Cu complexes immobilized on solid surfaces with organic functionalities for the efficient transformation of organic molecules. In the case of concerted catalysis with Pd complexes, the allylation of nucleophiles was shown to be effectively accelerated by the assistance of a basic amine group: both allylic substrates and nucleophiles were activated by Pd complexes and bases, respectively …”

Section: Figurementioning

confidence: 99%

Concerted Catalysis in Tight Spaces: Palladium‐Catalyzed Allylation Reactions Accelerated by Accumulated Active Sites in Mesoporous Silica

et al. 2017

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The surface of mesoporous silica was modified with a Pd–bisphosphine complex and/or a tertiary amine group for concerted acceleration of allylation reactions. Mesoporous‐silica‐supported catalysts with a 1.6 nm pore diameter showed higher performance than nonporous or larger mesoporous silica‐supported catalysts owing to the accumulation of active sites into a confined space. For the case in which allyl alcohol was used in the reaction, the presence of a silanol group on the surface was quite effective: the turnover number of Pd was nine times greater than that of the homogeneous Pd complex.

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Section: Figurementioning

confidence: 99%

Concerted Catalysis in Tight Spaces: Palladium‐Catalyzed Allylation Reactions Accelerated by Accumulated Active Sites in Mesoporous Silica

et al. 2017

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“…Moreover, recycling of CT13* was obstructed by deactivation as a consequence of transformation of the pyrrolidine secondary amino group. A chiral heterogeneous catalyst containing both an achiral metal complex and CA6* immobilized on SiO 2 support (CT14*, Scheme 28) was developed by Córdova and coworkers 162 for heterogeneous synergistic catalysis of the asymmetric Michael addition and intramolecular carbocyclization cascade reaction described initially using soluble organocatalyst (see Scheme 3 (ref. 97)).…”

Section: One-pot Reactions Using Heterogenized Chiral Organocatalystsmentioning

confidence: 99%

Asymmetric one-pot reactions using heterogeneous chemical catalysis: recent steps towards sustainable processes

Szőllősi

2018

Catal. Sci. Technol.

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The preparation of optically pure fine chemicals is among the most important and challenging tasks met by organic chemists. Recently, significant efforts have been focused on the development of green and sustainable procedures for the synthesis of these high value-added compounds. Asymmetric heterogeneous catalysis has provided efficient solutions to these challenges. The application of heterogeneous chiral catalysts in one-pot processes combines the advantages of use of these materials with time, material, and energy savings associated with cascade or sequential procedures. This review surveys these asymmetric onepot reactions reported until July 2017, in which a heterogeneous chemical catalyst has been applied either as a single multifunctional catalyst or in combination with a second catalytically active material. These processes include one-pot procedures catalysed by carefully designed solids obtained by the immobilization of chiral metal complexes, by anchoring chiral organocatalysts, or by modifying catalytic surfaces with optically pure compounds, which may also incorporate uncatalyzed and homogeneously catalysed steps. Methods applying achiral heterogeneous catalysts in combination with soluble chiral chemical catalysts or biocatalysts are also presented. Sophisticated, finely tuned materials have been applied in most of these reactions, which have been discussed along with the main requirements necessary to perform these transformations in a one-pot manner.

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“…All of these features characterize a sustainable and eco-friendly technology. Based on the above challenges and our previous experience in developing palladium based heterogenous catalysts for various green chemical transformations [23][24][25][26][27][28][29] , we designed an eco-friendly approach for the preparation of heterogeneous and multifunctional palladium catalysts suitable for a wide spectrum of chemical transformations. The activity and versatility of the designed catalysts was demonstrated in the Suzuki-Miyaura cross-coupling reaction, aerobic oxidation approach of allylic alcohols and stereoselective cascade carbocyclization reactions (Fig.…”

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confidence: 99%

Sustainable and recyclable heterogenous palladium catalysts from rice husk-derived biosilicates for Suzuki-Miyaura cross-couplings, aerobic oxidations and stereoselective cascade carbocyclizations

Afewerki

Franco

Balu

et al. 2020

Sci Rep

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A new eco-friendly approach for the preparation of sustainable heterogeneous palladium catalysts from rice husk-derived biogenic silica (RH p-Si and RH U-Si). the designed heterogeneously supported palladium species (RH p-Si-nH 2-pd and RH U-Si-nH 2-pd) were fully characterized and successfully employed as catalysts for various chemical transformations (c-c bond-forming reactions, aerobic oxidations and carbocyclizations). Suzuki-Miyaura transformations were highly efficient in a green solvent system (H 2 O:EtOH (1:1) with excellent recyclability, providing the cross-coupling products with a wide range of functionalities in high isolated yields (up to 99%). Palladium species (Pd(0)nanoparticles or Pd(II)) were also efficient catalysts in the green aerobic oxidation of an allylic alcohol and a co-catalytic stereoselective cascade carbocyclization transformation. in the latter case, a quaternary stereocenter was formed with excellent stereoselectivity (up to 27:1 dr). Rice husk (RH) is a major waste product from the rice industry with high content of silica. This abundant material is a sustainable and cheap raw material and therefore within the context of sustainability 1. De facto, rice husk ash (RHA) is known to contain 94% silica 2. Here, silica is a very important component for various industrial and biomedical applications 3 , being high surface area silicates highly desirable and good candidates as catalyst support 4. For these reasons the development of efficient methods for the preparation of silica and silica based materials are of high interest. In general, the production of silica from RH is energy intensive i.e. obtained by burning RH in a muffle furnace at high temperature (500, 600 or 700 °C) 5,6. Nevertheless, even though there are some reports on simple and energy-efficient method for the generation of silica from RH, drawbacks such as risk for mineral contamination 7 , several acid and based extraction steps or tedious approaches 8 are encountered 9. In this context, novel methods for the extraction of silica in an eco-friendly, cost-efficient, scalable and facile approach can be highly attractive. This report discloses the preparation of palladium based multifunctional heterogenous catalysts from RH-derived silica as support. There are reports on the immobilization of various metals on RH and their use as heterogeneous catalysts for chemical syntheses 10-16. In this context, Chang and co-workers

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Enantioselective Heterogeneous Synergistic Catalysis for Asymmetric Cascade Transformations

Cited by 55 publications

References 80 publications

Concerted Catalysis in Tight Spaces: Palladium‐Catalyzed Allylation Reactions Accelerated by Accumulated Active Sites in Mesoporous Silica

Concerted Catalysis in Tight Spaces: Palladium‐Catalyzed Allylation Reactions Accelerated by Accumulated Active Sites in Mesoporous Silica

Asymmetric one-pot reactions using heterogeneous chemical catalysis: recent steps towards sustainable processes

Sustainable and recyclable heterogenous palladium catalysts from rice husk-derived biosilicates for Suzuki-Miyaura cross-couplings, aerobic oxidations and stereoselective cascade carbocyclizations

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