Dithianylium Salts as Versatile Reagents for Organofluorine Chemistry: Fluorodesulfuration in the Presence of Various O- and N-Nucleophiles

Abstract

Dithianylium salts in combination with oxidative fluorodesulfuration chemistry act as a versatile new class of α,α‐difluoroalkylation reagents, allowing for the first time the convenient synthesis of complex α,α‐difluoroethers or α‐fluoroacetals. Even relatively fragile species, such as α,α‐difluoroalkyl azides or peroxides, can be obtained under very mild reaction conditions. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Synthesis, Stability and Reactivity of α‐Fluorinated Azidoalkanes

“…Kirsch and Taugerberg have described the synthesis of α,α‐difluoroazidoalkanes for liquid crystal application from dithianylium triflates and trimethylsilyl azide in the presence of fluoride anions and electrophilic brominating agent 1,3‐dibromo‐5,5‐dimethylhydanthoin (DBH) (Scheme ) …”

Dibromofluoromethylation of aryl Grignard reagents with dibromodifluoromethane in the presence of LiBr

“…The nucleophilic substitution reaction of 8k with 4-nitorophenoxide afforded a 70% yield of diphenylacetal 12. While this method was not applicable to the reaction of catechol, cyclic acetal 13 [20] was obtained in 67% yield by heating of 8k in the presence of 2,2'-dihydroxybiphenyl and K 2 CO 3 . …”

Fluoro-Pummerer rearrangement and analogous reactions

“…While a large array of functional groups is tolerant to the reaction, ketones required protection of the carbonyl group, usually accomplished by transforming it to the corresponding acetal [140]. In a similar 164 16 [142,143]. The reaction of ketene dithioacetals 180 with alcohols and subsequent desulfurization-fluorination of 181 with DBH and Et 3 NÁ3HF at À70 8C afforded a,adifluoroalkylethers 182.…”