Quaternary ammonium fluorides and difluorosilicates as nucleophilic fluorination reagents.

Trojan, Michal; Kucnirová, Katerina; Bouzková, Sárka; Cvacka, Josef; Cejka, Jan; Tavcar, Gasper; Rybácková, Markéta; Kvícala, Jaroslav

Trojan, Michal; Kucnirová, Katerina; Bouzková, Sárka; Cvacka, Josef; Cejka, Jan; Tavcar, Gasper; Rybácková, Markéta; Kvícala, Jaroslav.

Afiliación

Trojan M; Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic. kvicalaj@vscht.cz.
Kucnirová K; Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic. kvicalaj@vscht.cz.
Bouzková S; Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic. kvicalaj@vscht.cz.
Cvacka J; Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo námestí 542/2, 160 00 Prague 6, Czech Republic.
Cejka J; Department of Solid State Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Tavcar G; Department of Inorganic Chemistry and Technology, "Jozef Stefan" Institute, Jamova cesta 39, Ljubljana, Slovenia.
Rybácková M; Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic. kvicalaj@vscht.cz.
Kvícala J; Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic. kvicalaj@vscht.cz.

Org Biomol Chem ; 22(5): 1047-1056, 2024 Jan 31.

Article en En | MEDLINE | ID: mdl-38197465

ABSTRACT

ABSTRACT

TBAT (tetrabutylammonium difluorotriphenylsilicate) is an excellent homogeneous nucleophilic fluorination reagent, but a high excess of the reagent was reported to be essential. We hence optimized the reaction conditions and compared its nucleophilic fluorination reactivity with that of other common commercial nucleophilic fluorination reagents, such as anhydrous TBAF and TASF (tris(dimethylamino)sulfonium difluorotrimethylsilicate). As the substrates, we employed a standard set of primary and secondary octyl substrates under identical conditions. To eliminate the possibility of hydrogen fluoride elimination in the above reagents, we prepared four quaternary ammonium fluorides lacking ß-elimination possibility in the hydrocarbon chain, transformed them to the corresponding difluorotriphenylsilicates, and compared their reactivity with that of the commercial reagents. Furthermore, attempts to isolate analogous tetrabutylammonium difluoromethyldiphenylsilicate or difluorodimethylphenylsilicate failed, as was confirmed by comparison of the published experimental data with computed 19F NMR spectra. Finally, we studied the transition states of decomposition of various tetramethylammonium methylphenyldifluorosilicates by DFT methods and found that their relative energies increase with an increasing number of phenyl groups. The formation of difluorosilicates is a nearly barrierless process.

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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Org Biomol Chem Asunto de la revista: BIOQUIMICA / QUIMICA Año: 2024 Tipo del documento: Article País de afiliación: República Checa Pais de publicación: Reino Unido

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