C(sp2)-H Borylation of Heterocycles by Well-Defined Bis(silylene)pyridine Cobalt(III) Precatalysts : Pincer Modification, C(sp2)-H Activation and Catalytically Relevant Intermediates
Well-defined bis(silylene)pyridine cobalt(III) precatalysts for C(sp2)-H borylation have been synthesized and applied to the investigation of the mechanism of the catalytic borylation of furans and pyridines. Specifically, [( Ar SiNSi)CoH3]·NaHBEt3 ( Ar SiNSi = 2,6-[EtNSi(NtBu)2CAr]2C5H3N, Ar = C6H5...
| Veröffentlicht in: | Organometallics. - 1998. - 39(2020), 14 vom: 27. Juli, Seite 2763-2773 |
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| Weitere Verfasser: | , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2020
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| Zugriff auf das übergeordnete Werk: | Organometallics |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Well-defined bis(silylene)pyridine cobalt(III) precatalysts for C(sp2)-H borylation have been synthesized and applied to the investigation of the mechanism of the catalytic borylation of furans and pyridines. Specifically, [( Ar SiNSi)CoH3]·NaHBEt3 ( Ar SiNSi = 2,6-[EtNSi(NtBu)2CAr]2C5H3N, Ar = C6H5 (1-H 3 ·NaHBEt 3 ), 4-MeC6H4 (2-H 3 ·NaHBEt 3 )) and trans-[( Ar SiNSi)Co(H)2BPin] (Ar = C6H5 (1-(H) 2 BPin), 4-MeC6H4 (2-(H) 2 BPin), Pin = pinacolato) were prepared and employed as single component precatalysts for the C(sp2)-H borylation of 2-methylfuran, benzofuran and 2,6-lutidine. The cobalt(III) precursors, 2-H 3 ·NaHBEt 3 and 2-(H) 2 BPin also promoted C(sp2)-H activation of benzofuran, yielding [(ArSiNSi)CoH(Bf)2] (Ar = 4-MeC6H4, 2-H(Bf) 2 , Bf = 2-benzofuranyl). Monitoring the catalytic borylation of 2-methylfuran and 2,6-lutidine by 1H NMR spectroscopy established the trans-dihydride cobalt(III) boryl as the catalyst resting state at low substrate conversion. At higher conversion two distinct pincer modification pathways were identified, depending on the substrate and the boron source |
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| Beschreibung: | Date Revised 01.08.2024 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 0276-7333 |
| DOI: | 10.1021/acs.organomet.0c00382 |