Electrolytic Partial Fluorination of Organic Compounds. 12. Selective Anodic Monofluorination of Fluoroalkyl and Alkyl Sulfides

Abstract

Highly regioselective anodic monofluorination of various aryl and alkyl fluoroalkyl sulfides was successfully carried out, and fluorine was exclusively (aryl sulfides) or preferentially (alkyl sulfides) introduced at the position a to the fluoroalkyl group. Even simple alkyl phenyl sulfides devoid of an electron-withdrawing group could be anodically monofluorinated in satisfactory yields for the first time when etheral solvents were used as an electrolytic solution. A unique Pummerer-type mechanism via fluorosulfonium ions was proposed for this anodic fluorination by comparison with anodic -methoxylation previously studied.

Electrochemical partial fluorination of organic compounds: 81. Regioselective anodic fluorination of O-methyl S-aralkyl thiocarbonates

“…Since the sulfur atom was found to be the most easily oxidized in the thiocarbonate molecules 1, anodic fluorination seems to proceed via a fluorosulfonium ion intermediate A as proposed previously (Scheme 4) [23]. The difluoro product 3 seems to be formed from 2 in a similar manner as shown in Scheme 4.…”

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).…”

Electrolytic partial fluorination of organic compounds

“…Since the sulfur atom of tetrazolyl sulfides is most easily oxidized, the initial electron transfer should take place at the sulfur atom and the reaction seems to proceed via a Pummerer type mechanism as proposed previously (Scheme 5) [20]. Selectfluor and N-fluoropyridinium salts derived from fluorine gas are known to be fluorinating reagents of sulfides, however they are not suitable for large-scale fluorination.…”