Oxidative fluorination of sulfur(IV) compounds by XeF2

(Hetero)aryl‐SVI Fluorides: Synthetic Development and Opportunities

“…At this point, two pathways can be envisaged. As already reported by Janzen and Ou, [22, 23] chlorine radicals (or Cl 2 ) and fluoride anions are formed when XeF 2 is mixed with chloride anions. Therefore, in path a (Scheme 15), fluoride anions react with Lewis acidic Ar−SF 3 , and after oxidation and radical coupling with a chlorine radical, the trans isomer is formed.…”

“…Oxidative fluorination of aryl-S(IV) compounds such as diphenyl sulfoxide or diphenylsulfur difluoride occurs under mild conditions in the presence of XeF 2 and catalytic amounts of chloride anions. [22] In this manner, diarylsulfur-(VI) difluorides were obtained in quantitative yields and in short reaction times. Mechanistically, it was postulated that a Cl-mediated activation of XeF 2 for the oxidative fluorination of diarylsulfoxides would initiate the reaction, which would be followed by a radical chain reaction propagated by Ph 2 S(O * )F species.…”

“…A breakthrough in the synthesis of aryl‐S VI difluorides was made in the same year by Janzen and Ou (Scheme 6). Oxidative fluorination of aryl‐S(IV) compounds such as diphenyl sulfoxide or diphenylsulfur difluoride occurs under mild conditions in the presence of XeF 2 and catalytic amounts of chloride anions [22] . In this manner, diarylsulfur(VI) difluorides were obtained in quantitative yields and in short reaction times.…”

Electrophilic fluorosulfoxonium cations as hidden Brønsted acid catalysts in (n + 2) annulations of strained cycloalkanes

“…15 This Umpolung strategy for phosphines was extended to sulfoxides to form fluorosulfoxonium cations (Figure 1), 15 which were already known species. [16][17][18] However, electrophilic sulfoxonium cation-based catalysis is yet to be fully developed beyond hydroarylation, hydrothiolation and polymerisation of THF. 15 Considering their high Lewis acidity and their apparent σ and π activating nature, we reasoned that annulation reactions with polarised cycloalkanes ought to be feasible and an interesting new application of ESC catalysis.…”

“…15 The first step is the oxidative difluorination with XeF 2 in the presence of catalytic NEt 4 Cl. 17,18 The second step is the monodefluorination with an external fluorophile. Both steps are performed sequentially, without change of the solvent.…”