New mechanistic aspects of anodic monofluorination of halogenoalkyl and alkyl phenyl sulphides

Abstract

A unique Pummerer type mechanism via fluorosulphonium ions for anodic monofluorination of sulphides is established by comparing the anodic monofluorination of partially halogenated ethyl phenyl sulphides (1, PhSCH2R; R = CF3, CF2H, CFH2, CF2CI, CCIH2) with their anodic methoxylation; simple alkyl phenyl sulphides 2 bearing no electron-withdrawing group could be monofluorinated anodically in satisfactory yields for the first time when tetrahydrofuran was used as a solvent.

Electrolytic partial fluorination of organic compounds. 77. Reactivity of anodically generated benzylic cation intermediates toward fluoride ions in acetonitrile

“…On the other hand, we found that a-electron-withdrawing groups promoted the anodic a-fluorination of organosulfur and selenium compounds as shown in [17][18][19][20]. Simonet and co-workers [21] also reported that anodic a-fluorination of alkyl phenyl sulfides was promoted by an electron-withdrawing group on the benzene ring as shown in Scheme 4(b).…”

Fluoro-Pummerer rearrangement and analogous reactions

“…Selective electrochemical fluorination to form 42 of phenyl 2,2,2-trifluoroethyl sulfide [74], a-(phenylthio)acetate and related organosulfur compounds, bearing electron withdrawing groups was successful in acetonitrile containing Et 3 NÁ3HF (Scheme 22) [75].…”

Electrochemical strategies for C–H functionalization and C–N bond formation

“…293 Electrochemical fluorination of arylsulfides constitutes another transformation that has been extensively studied by several research groups. Early work during the 1990s from the Fuchigami [294][295][296][297][298][299][300][301][302] (Scheme 27) and Laurent 303,304 (Scheme 28) laboratories demonstrated that the introduction of an electronwithdrawing group at the a-position to sulfur had a dramatic influence on the reactions. These a-fluorination transformations were believed to proceed through a Pummerer-type mechanism where the electron-withdrawing group facilitates deprotonation of the a-carbon to produce intermediate 110, thereby promoting fluorination.…”