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Ru-Catalysed C-H Silylation of Gramines, Tryptamines and their Congeners
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Organisk kemi. (Pilarski Research Group)
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Organisk kemi. (Pilarski Research Group)
Univ Bristol, Sch Chem, Bristol BS8 1TS, Avon, England.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Organisk kemi. (Pilarski Research Group)ORCID-id: 0000-0002-9353-2238
2016 (engelsk)Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, nr 34, s. 5868-5871Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Selective Ru-catalysed C2–H silylation of heteroarenes is presented. The transformation works with or without directing group assistance and requires no protecting groups. Gramines and tryptamines may be converted efficiently whilst avoiding deleterious elimination side-reactions. Mechanistic studies reveal an unusual activation of the indole C4–H bond by an electron-rich metal.

sted, utgiver, år, opplag, sider
Royal Society of Chemistry, 2016. Vol. 52, nr 34, s. 5868-5871
HSV kategori
Forskningsprogram
Kemi med inriktning mot organisk kemi
Identifikatorer
URN: urn:nbn:se:uu:diva-286545DOI: 10.1039/C6CC00803HISI: 000374396500022PubMedID: 27050747OAI: oai:DiVA.org:uu-286545DiVA, id: diva2:921686
Forskningsfinansiär
Swedish Research CouncilTilgjengelig fra: 2016-04-20 Laget: 2016-04-20 Sist oppdatert: 2017-11-30bibliografisk kontrollert
Inngår i avhandling
1. Ruthenium-catalyzed C-H Functionalization of (Hetero)arenes
Åpne denne publikasjonen i ny fane eller vindu >>Ruthenium-catalyzed C-H Functionalization of (Hetero)arenes
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis concerned about the Ru-catalyzed C-H functionalizations on the synthesis of 2-arylindole unit, silylation of heteroarenes and preparation of aryne precursor.

In the first project, we developed the Ru-catalyzed C2-H arylation of N-(2-pyrimidyl) indoles and pyrroles with nucleophilic arylboronic acids under oxidative conditions. Wide variety of arylboronic acids afforded the desired product in excellent yield regardless of the substituents or functional group electronic nature. Electron-rich heteroarenes are well suited for this method than electron-poor heteroarenes. Halides such as bromide and iodide also survived, further derivatisation of the halide is shown by Heck alkenylation. In order to find catalytic on-cycle intermediate extensive mechanistic experiments have been carried out by preparing presumed ruthenacyclic complexes and C-H/D exchange reactions. It suggested that para-cymene ligand is not present in the catalytic on-cycle intermediate and we suspect that metalation occurs with electrophilic ruthenium center via SEAr mechanism.

In the second project, we developed the Ru-catalyzed silylation of gramine, tryptamine and their congeners using silanes as coupling partner. The transformation worked well with many different silanes. Regarding directing group, nitrogen atom containing directing groups are more favoured than the oxygen containing directing groups. Wide range of gramines and tryptamines also yielded the desired product in poor to excellent yield. At higher temperature, albeit in low yield, undirected silylation occurred. In order to get some insights about the reaction pathway of the silylation C-H/D exchange experiments were performed, and it revealed the possibility of C4-H activation of gramines by an electron rich metal- Si-H/D experiments showed Si-H activation by Ru is easy.

In the final project, we presented the closely related aryne precursors from arylboronic acids via Ru-catalyzed C-H silylation of arylboronates and their selective oxidation. Worthy of note, the aryne capture products obtained from arylboronic acids in a single purification.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2017. s. 59
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1465
Emneord
catalysis, C-H activation, heterocycles, ruthenium, aryne precursor, silylation, gramine
HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-310998 (URN)978-91-554-9783-5 (ISBN)
Disputas
2017-02-24, B22, BMC, Husargatan 3, Uppsala, Uppsala, 09:30 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2017-02-03 Laget: 2016-12-20 Sist oppdatert: 2017-02-07
2. New Arylation Strategies Based on Organomain Group Reactivity
Åpne denne publikasjonen i ny fane eller vindu >>New Arylation Strategies Based on Organomain Group Reactivity
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The work in this thesis describes the development of new heteroarylation methodology based on transition metal-catalysed C-H functionalisation and the properties of organomain group compounds. The underlying reaction mechanisms and reactivity patterns of the (hetero)arene substrates are also investigated. The selective C2-H arylation indoles, which are key pharmaceutically-relevant units, was achieved using N-pyrimidyl directing groups, RuII catalysis and arylboronic acids as the coupling reagents (paper I). The use of this set of conditions enabled a remarkable functional group tolerance, highlighted by the preservation of halide substituents on both coupling partners. Mechanistic experiments suggest that cleavage of the C2-H bond occurs through an electrophilic aromatic substitution type pathway. The dehydrogenative C2-H silylation of unprotected gramine and tryptamine alkaloids and other related heteroarenes using hydrosilanes under Ru0 catalysis is described in paper II. The protocol does not require protecting groups and undirected C2-H silylation of heteroarenes is possible at higher temperatures. Significantly, H/D-exchange studies revealed deuterium incorporation at the C4 and C7 positions of the indole unit, apart from C2-H silylation. This study represents the first account of C4-H activation using an electron-rich metal catalyst. Paper III describes an unexpected and profound influence of boronate substituents on the regioselectivity of aryne trapping reactions. The boronates may be introduced easily to the backbone of established fluoride-activated precursors via Ir-catalysed C-H functionalisation. Optimisation and mechanistic studies on the unprecedented level of regioselectivity control these substituents permit using external additives is presented.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2017. s. 80
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1552
Emneord
C-H functionalisation, catalysis, ruthenium, indole, silylation, boronate, boryl aryne, aryne distortion
HSV kategori
Forskningsprogram
Kemi med inriktning mot organisk kemi
Identifikatorer
urn:nbn:se:uu:diva-328750 (URN)978-91-513-0055-9 (ISBN)
Disputas
2017-10-20, B21, Biomedical Centre (BMC), Husargatan 3, Uppsala, 13:30 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2017-09-29 Laget: 2017-08-31 Sist oppdatert: 2017-10-17

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