Sulfenyl fluorides

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... 

Perfluorohalogenoorganosulfenyl halides are, like thiols, mercaptides, and thioketones, key compounds for the synthesis of new perfluorohalo-genoorganomercapto derivatives. The high reactivity of the S—X bond (X = Cl, Br) toward electrophilic as well as nucleophilic reagents causes them to be highly valued starting materials for the synthesis of new derivatives. The chemistry of the not very stable sulfenyl fluorides has... 

Chemical Shifts and Coupling Constants fob Liquid Sulfenyl Fluorides... 

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) ... 

The compound isomeric with perfluoropropane-1-sulfenyl fluoride is formed by the p3Tolysis of [(CFslgCFJgSFg 136) ... 

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) ... 

All compounds, except the slightly green (CFglgCFSF, are colorless liquids or colorless gases above their boiling points. The sulfenyl fluorides, CF Cl3 SF (n = 0, 1, 2, 3), are stable for some time in the liquid phase at —50°C and in the gaseous state at low pressures ( 10 torr, 20°C). 

This indirect proof of the appearance of CF3SF leads to the conclusion that fluorination of sulfenyl chlorides of the series CF Cl3 SCl (n = 0, 1, 2) with alkali metal fluorides follows the mechanism observed in the formation of sulfenyl fluorides the initial chlorine-fluorine exchange at the sulfur atom is followed by isomerization to the sulfenyl chloride containing the corresponding more highly fluorinated methyl group. 

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

Sulfenyl Fluoride, Trifluoronietltane V/3,201 (CI3C - S - Cl + HgF2) ElOb,. 368 (Educt)... 

Trifluoromethyl)sulfenyl fluoride undergoes addition to propene or 3,3,3-trifluoropropene to yield the sulfides 1 and 2. ... 

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. 

Further, the metal fluorides SbFs (with admixture of small quantities of SbCls), HgF2, and AgF are also found suitable for the fluorination of sulfenyl halides, e.g.. 

Trifluoromethylthiocarbonyl fluoride can be converted to the chloride by halogen exchange with aluminum trichloride. By chlorine addition this compound furnishes another sulfenyl chloride (55) ... 

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... 

Addition of a sulfenyl chloride to an alkene in the presence of silver fluoride affords (3-fluoro sulfides, as shown in equation (2).18 The same trans adducts can also be prepared from the sulfenyl chloride adducts and silver fluoride. An alternative procedure for the formal addition of methanesulfenyl fluoride to alkenes involves the use of dimethyl(methylthio)sulfonium tetrafluoroborate and triethylamine tris(hy-drofluoride) as in equation (3).19... 

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.

Fluorinated thioketones <1965JOC1390> and perhalogenoalkylthioacetyl fluorides <1992CB1889> are reactive dienophiles and rapidly add across the 9,10-bond of anthracene to form the isothiochroman nucleus 494 (Equation 170). Similar products result from the treatment of the sulfenyl chloride 495 with triethylamine when a thioaldehyde is generated (Scheme 182) <1991J(P1)3225>. 

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. ... 

Table 38. Addition of Sulfenyl Chlorides to Alkenes in the Presence of Alkali Fluoride...

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. 

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