Vinyl sulfides fluorination

D.F. Andres, U. Dietrich, E.G. Laurent, B.S. Marquet, Anodic fluorination of vinyl sulfides - synthesis of a-fluoro- -thio-a, -unsaturated carbonyl compounds. Tetrahedron 53 (1997) 647-658. 

The anodic oxidation of a number of vinyl sulfides to produce fluorinated compounds was examined in MeCN-Et3N 3HF on Pt electrodes under controlled-potential conditions [130]. It became evident that the reactivity of the vinyl thioethers depends on, among others, their structure and the nucleophilicity of the medium. Two compounds, PhSCH = CH2 and PhSCH=CHPh, were studied in more detail to evaluate the influence of the different factors upon their electrochemical behavior, and comparisons with that in MeOH Et N 3HF and HOAc-KOAc, leading, respectively, to methoxylation and acet-oxylation were made (Table 3). 

Anodic oxidation of olefins in the presence of fluoride ions provides mono- and/or difluorinated products [Eqs (2) and (7)] [10,33,34]. Butadiene gives a 1 2 mixture of 1,2-and 1,4-adducts [35]. Anodic fluorination of vinyl sulfides such as 2-(phenylthio)styrene provides vicinal difluorides [36]. 

Kovregin AN, Sizov AY, Ermolov AF (2002) Synthesis of substituted thiophenes based on fluorine-containing p-functionalized vinyl sulfides. Russ Chem BuU (Engl Transl) 51 1028-1030... 

Benzylthio-3-cyanoquinolines bearing fluorine atom in position 4 have been obtained on heating of functionalized N-vinyl anilines 53 the latter are prepared by condensation of the corresponding a-fluorine-containing vinyl sulfides with anilines (Scheme 20) [31], Alkaline hydrolysis of the reaction products afforded the corresponding 3-cyanoquinolin-4-ones 54. 

Scheme 20 Condensation of a-fluorine-containing vinyl sulfides with anilines...

Kovregin A, Sizov A, Ermolov A (2002) Reactions of a-fluorine-containing P-functionalized vinyl sulfides with N-nucleophiles. Rus Chem Bull 51 1020-1027... 

As for the base-promoted thioetheriiication, Shen and Wang reported in 2005 that highly electrophilic alkenes such as fluorinated vinylstannanes 172 could be converted to fluorinated vinyl sulfides 173 with ( )-selectivity via a nucleophilic addition of thiols to alkenes and defluorination 174 followed by destannylation (Scheme 46.22). In 2008, Cordova developed an organocatalytic enantioselec-tive aminosulfenylation of a,(3-unsaturated aldehydes 175 using A -(benzylthio)succinimides 176 in the presence of a TMS-protected chiral diarylprolinol. ° The reaction proceeded with low diastereoselectivities but with excellent enantioselectivities. The reason for the low diastereoselec-tivity might lie in the rapid epimerzation of Ca-H bond under the enamine catalysis 178. 

Hydrolysis is probably a more complex process, since 3,4-bis(trifluoro-methyl)perfluorohexa-2,4-diene gives a cyclic product—perfluorotetra-methylfuran 46 (94JCS(P1)3119, 90JCS(CC)1127). The reaction involves vinyl substitution of fluorine with subsequent fast electrocyclization of the intermediate carbanion accompanied by fluoride ion elimination. An analogous reaction of 3,4-bis(trifluoromethyl)perfluorohexa-2,4-diene with sodium sulfide or thiourea forms perfluorotetramethylthiophene 47 (90JCS(CC)1127). 

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