Reactivity of Electrophilic Trifluoromethylating Reagents

Timofeeva, Daria S. ; Puente, Ángel ; Ofial, Armin R. und Mayr, Herbert (2024): Reactivity of Electrophilic Trifluoromethylating Reagents. In: European Journal of Organic Chemistry, Bd. 27, Nr. 13

Abstract

Kinetics of the reactions of colored carbanions (reference nucleophiles) with S-(trifluoromethyl)dibenzothiophenium ions (Umemoto's reagents) and hypervalent trifluoromethyl-substituted iodine compounds (Togni's reagents) have been determined photometrically using stopped-flow techniques. The second-order rate constants k2(20 °C) for the reactions of Umemoto's sulfonium ions (generation I and II) with the reference nucleophiles in DMSO follow the correlation lg k2(20 °C)=sN(N+E) and can be used to determine the electrophilicity parameters E of these trifluoromethylating reagents. It is shown that the conditions reported for the reactions of Umemoto's generation I reagents with a variety of C-nucleophiles are in line with the electrophilicity parameter E≈−13 determined for these reagents. Though Togni's hypervalent iodine-based trifluoromethylation reagents do not follow this linear free energy relationship, the kinetics of their reactions with carbanions indicate that they cover the same reactivity range as Umemoto's generation I and II reagents.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 1434-193X
• Sprache: Englisch