Sulfenyl fluorides reaction

Sulfenyl fluorides are extremely unstable and therefore only few perhalosulfenyl fluorides have so far been reported122. The formal addition of the elements of methanesulfenyl fluoride to carbon-carbon double bonds has been obtained123 by a one-pot reaction with dimethyl(methylthio)sulfonium tetrafluoroborate and triethylammonium tris(hydrofluo-ride). With this system also the addition to double bonds is highly stereoselective, at least... 

The best method for the preparation of CF3SF is the reaction of CFgSCl with HgFg in a nickel or platinum apparatus at 130°C, followed by removal of the reaction products by condensation in liquid nitrogen 144). Analogous reactions with metal fluorides lead to other sulfenyl fluorides 102,189) ... 

A further reaction of general importance, the cleavage of disulfanes by means of a fluorinating agent, provides in the case of perfluoroaryl disulfanes the sulfenyl fluorides in good yield 33) ... 

The relatively stable sulfenyl fluoride eventually combines in a competing reaction with unreacted (CF3S)2C=S to give (CF8S)2C(F)SSCF8. 

In perchloryl fluoride (FCIO3) the fluorine is a soft acid. Formation of the C-F bond is observed when it is treated with carbanions. Thiolates are oxidized to disulfides by this reagent (92, 93). This latter reaction presumably involves sulfenyl fluoride intermediates. In contrast, alkoxide ions effect displacement at chlorine to afford perchlorate esters or further transformation products. 

Fluoride ion attacks the sulfur atom in 2,3-diphenylthiirene 1,1-dioxide to give ck-1,2-diphenylethylenesulfonyl fluoride (23%) and diphenylacetylene (35%). Bromide or iodide ion does not react (80JOC2604). Treatment of S-alkylthiirenium salts with chloride ion gives products of carbon attack, but the possibility of sulfur attack followed by addition of the sulfenyl chloride so produced to the alkyne has not been excluded (79MI50600). In fact the methanesulfenyl chloride formed from l-methyl-2,3-di- -butylthiirenium tetrafluoroborate has been trapped by reaction with 2-butyne. A sulfurane intermediate may be indicated by NMR experiments in liquid sulfur dioxide. 

Chlorodifluorothioacetyl fluoride prepared by this reaction has a boiling point of 23° C. NMR characterization of this compound gave a low-field triplet and high-field doublet in a ratio of 1 2, as would be expected. However, a material boiling at 36° C had been reported earlier as chlorodifluorothioacetyl fluoride (54). This material was obtained by dehalogenation erf 2-chlorotetrafluoroethane-sulfenyl chloride with tin. In view of... 

In conclusion, SNAr reactions are often facihtated by polar protic solvents such as butanol or by polar solvents in the presence of Brpnsted or Lewis acids. When displacements of halides with amines are used, both polar and protic solvents can solubilize the ammonium halides resulting from the reactions, and lead to the formation of Brpnsted acids. Fluoride or chloride ions are preferred leaving groups for this reaction. Suliinyl and sulfenyl groups require somewhat harsher conditions. 

Fig. 4. Danishefsky s total synthesis formation of cyclobutanone, sulfenylation, and successive oxidation reactions. DME = 1,2-dimeth-oxyethane, TBAF = tetra-n-butylammonium fluoride, NMO = A/-methyl-morpholine-N-oxide.

The reaction of fluoro- or chlorofluoroalkenes with the sulfur tetrafluoride/hydrogen fluoride/ sulfur monochloride system leads to perfluoroalkanesulfenyl chlorides, (sulfanyl)sulfenyl chlorides, sulfides and polysulfides. Tetrafluoroethene reacts with sulfur tetrafluoride/hydrogen fluoride in the presence of 1 equivalent of sulfur monochloride at 80°C to yield a mixture of pentafluoroethanesulfenyl chloride (4), (pentafluoroethanesulfanyl)sulfenyl chloride... 

Further examples of the preparation of fluorinated sulfides from the reaction of alkenes with sulfenyl chlorides in the presence of alkali fluorides are presented in Table 38. ... 

A similar reaction via addition-elimination occurs with diethoxythioxaphosphorane sulfenyl bromide <1994SL267> or diethoxyoxophosphoranesulfenyl chloride <1997HAC429> and subsequent treatment of the 1,2-adduct with tetrabutylammonium fluoride (TBAF). The advantage of this protocol is the smooth formation of adducts of type 90 and their transformation into the corresponding thiiranes under neutral reaction conditions (Scheme 49). The entire sequence can be carried out as a one-pot reaction. 

When suitable conditions are provided, the chlorine atoms of trichloromethane-sulfenyl chloride can be selectively exchanged in succession for fluorine atoms by reaction with anhydrous hydrogen fluoride ... 

F -Anion exchange resins. Fluoride ion immobilized on strongly basic anion exchange resins, particularly Amberlyst A27 and Dowex MSA-1, promote the various reactions that have been found to be promoted by alkali metal or tetraalkylammonium fluorides, such as C- and O-alkylation, sulfenylation, and Michael additions. 

The insertion reaction between an isocyanide and a sulfenyl chloride generates an intermediate (e.g. equation 4.42), which can undergo 1,3-cycloaddition reactions with electron-deficient species to form pyrroles and pyrrolines. Potassium fluoride supported on alumina is a mild basic catalyst for this process [161]. 

Alkylation of j8-diketones using polymers as supports for the intermediate enolate anion has also been reported (Gelbard and Colonna, 1977). Reaction of several cyclohexyl j3-diketones with Amberlite IRA-9(K) formed a resin-linked j8-diketonate that could be readily alkylated. Similarly, it was shown that alkylation of phenoxide anions can be readily effected when the anions are supported via an ionic bond with the resin (Gelbard and Colonna, 1977). Alkylations of /3-diketones were also shown to occur if a fluoride-substituted, strongly basic resin (Amberlyst A26, A27, or Dowex MSA-1) is used (Miller et at., 1978). In this case, the presence of the fluoride ion was necessary before reaction would proceed. Considering the report on the use of Amberlite IRA-900— a very similar resin— the necessity for a fluoride ion is puzzling. In the same publication, the 0-alkylation of phenols, the sulfenylation of /3-diketones, and the Michael addition of a thiol to an ot,/8-unsaturated ketone were also investigated. 

Synthesis of Vinyl Aryl Sulfides. Vinyltrimethylsilane functions as an ethylene equivalent in electrophilic substitution reactions with sulfenyl chlorides (eq 1). Reaction with various arylsulfenyl chlorides provides the stable adducts (1) in high yield. Treatment of (1) with fluoride ion furnishes vinyl aryl sulfides (2) in high yield. 

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