Azulenesulfonium and azulenebis(sulfonium) salts: Formation by interrupted Pummerer reaction and subsequent derivatisation by nucleophiles

Alkylation Reactions with Alkylsulfonium Salts

“…23b Likewise, Lewis and coworkers described the synthesis of azulenylsulfides by ring opening reactions of cycloalkylazulenesulfonium salts with thiophenol anion and amines. 24 These strategies allowed convenient syntheses of a large number of useful alkyl(aryl)sulfides for future applications. [22][23][24] Scheme 9.…”

“…24 These strategies allowed convenient syntheses of a large number of useful alkyl(aryl)sulfides for future applications. [22][23][24] Scheme 9. Diverse ring-opening alkylation with alkylsulfonium salts in situ generated…”

“…24 These strategies allowed convenient syntheses of a large number of useful alkyl aryl sulfides for future applications. 22 23 24…”

“…This strategy was favorably applied in the three-component cascade reactions of aryne precursors, cyclic sulfides, and nucleophiles (HNu). 22 23 24 In 2016, Hoye and co-workers revealed the reaction of alkyl sulfide 47 with aryne 46 , thermally generated by the hexadehydro-Diels–Alder (HDDA) cycloisomerization of tetrayne 51 , produced an aryl anion bearing o -sulfonium moiety that underwent intramolecular proton transfer to form an S -aryl sulfur ylide 48 (Schemes 9a and 9b). 22 This species was trapped via sigmatropic shift or rearrangement to form sulfides 49 or protonated by weak acids (HNu) to produce alkylsulfonium intermediates.…”

Palladium-Catalyzed Fluoroalkylation via C(sp3)–S Bond Cleavage of Vinylsulfonium Salts

“…Unexpectedly, the reaction of a vinylsulfonium salt with CsF under palladium catalysis did not form the desired vinylic C–F bond through the cleavage of the vinylic C–S bond; instead, it underwent a fluoroalkylation process by cleavage of an aliphatic C–S bond. It has been known that S -alkyl tetrahydro-1 H -thiophen-1-ium salts and analogs can undergo ring-opening reactions with nucleophiles such as thiolates, azide, halogens, amines, and so on . Herein we disclose an interrupted Pummerer/palladium-catalyzed fluoroalkylation strategy for vinylic C–H fluoro-alkylthiolation via vinylsulfonium salts (Scheme b).…”