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Synthesis of Benzofurans and Indoles from Terminal Alkynes and Iodoaromatics Catalyzed by Recyclable Palladium Nanoparticles Immobilized on Siliceous Mesocellular Foam
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Swedish University of Agricultural Sciences, Sweden.ORCID-id: 0000-0003-2758-4811
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
Vise andre og tillknytning
2017 (engelsk)Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 52, s. 12886-12891Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Herein, we report on the utilization of a heterogeneous catalyst, consisting of Pd nanoparticles supported on a siliceous mesocellular foam (Pd-0-AmP-MCF), for the synthesis of heterocycles. Reaction of o-iodophenols and protected o-iodoanilines with acetylenes in the presence of a Pd nanocatalyst produced 2-substituted benzofurans and indoles, respectively. In general, the catalytic protocol afforded the desired products in good to excellent yields under mild reaction conditions without the addition of ligands. Moreover, the structure of the reported Pd nanocatalyst was further elucidated with extended X-ray absorption fine-structure spectroscopy, and it was proven that the catalyst could be recycled multiple times without significant loss of activity.

sted, utgiver, år, opplag, sider
2017. Vol. 23, nr 52, s. 12886-12891
Emneord [en]
benzofurans, extended x-ray absorption fine structure, heterogeneous catalysis, indoles, palladium
HSV kategori
Forskningsprogram
oorganisk kemi
Identifikatorer
URN: urn:nbn:se:su:diva-148090DOI: 10.1002/chem.201702614ISI: 000411033800029PubMedID: 28736879OAI: oai:DiVA.org:su-148090DiVA, id: diva2:1150873
Forskningsfinansiär
Swedish Research CouncilBerzelii Centre EXSELENTEU, European Research CouncilKnut and Alice Wallenberg FoundationTilgjengelig fra: 2017-10-20 Laget: 2017-10-20 Sist oppdatert: 2020-02-06bibliografisk kontrollert
Inngår i avhandling
1. Unveiling Catalytic Species in Suspension/Solution-Based Reactions by In Situ X-Ray Absorption Spectroscopy: Evolution of Palladium and Ruthenium Species
Åpne denne publikasjonen i ny fane eller vindu >>Unveiling Catalytic Species in Suspension/Solution-Based Reactions by In Situ X-Ray Absorption Spectroscopy: Evolution of Palladium and Ruthenium Species
2019 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The palladium (Pd) and ruthenium (Ru) species in several attractive catalysts have been probed using X-ray absorption spectroscopy (XAS). The study of catalyst evolution in suspension- and solution-based reactions was the primary aim. It was achieved by performing in situ XAS experiments on Pd and Ru over the course of the reactions. A custom-made reactor was employed which allowed the catalysts to be mixed with other reaction components under desired conditions.

The first system investigated was the Heck coupling reaction catalyzed by Pd(II) complexes embedded on metal-organic frameworks. It was realized that the as-synthesized catalysts go through an instant ligand substitution process when added to the reaction mixture. Mononuclear Pd complexes are the active species at the first stage of the measurement which then gradually transform into Pd nanoclusters. At a later stage of the measurement, chloride ligands start to bind to surface atoms of the Pd nanoclusters, leading to a deactivation of the catalyst. Following the first successful in situ XAS experiment, Pd(II) carbene complexes catalyzing undirected C–H acetoxylation of benzene in the presence of an oxidant were explored. A gradual ligand substitution occurs, and the mean oxidation state of Pd increases at the same time. At a later stage, Pd nanoclusters form, while the mean oxidation state of Pd returns to the start value. Deactivation of a heterogeneous Pd(II) catalyst during cycloisomerization of acetylenic acids was then investigated using in situ XAS. The choice of substrates showed to significantly influence the nature of Pd species, and the reduction of Pd(II) forming Pd(0) aggregates causes the deactivation. Moreover, strategies of reactivating the catalyst and prevention of the deactivation were developed and examined. In the end, the activation process of a Ru catalyst was studied and the structure of the intermediate was determined by in situ XAS. It was demonstrated that an electron-donating substituent on the cyclopentadiene ligand exhibits a promoting effect on the activation, while an electron-withdrawing substituent inhibits the activation.

sted, utgiver, år, opplag, sider
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2019. s. 112
Emneord
Palladium and ruthenium species, Catalysts, Suspension and solution, In situ X-ray absorption spectroscopy, Activation, Deactivation
HSV kategori
Forskningsprogram
oorganisk kemi
Identifikatorer
urn:nbn:se:su:diva-167340 (URN)978-91-7797-578-6 (ISBN)978-91-7797-579-3 (ISBN)
Disputas
2019-05-21, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 5: Manuscript. Paper 6: Manuscript.

Tilgjengelig fra: 2019-04-25 Laget: 2019-03-26 Sist oppdatert: 2019-04-12bibliografisk kontrollert

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