Sulfur dichloride, reaction with alkynes

Alkenes and alkynes react with sulfur dichloride (SC12), giving 2-chloroethyl(or vinyl)sulfenyl chlorides. The reaction is an electrophilic addition to the multiple bond, and consequently the possible intermediacy of thiiranes, or thiiranium ions analogous to bromonium ions, has been... 

The [S + C=C] route is illustrated by reaction of disulfur dichloride or sulfur dichloride with alkynes (Scheme 9), or by episulfidation of alkenes by sulfur atom donors in the presence of molybdenum oxocomplexes (Scheme 10) . 2-Phenylthiirane is the most efficient sulfur donor in the molybdenum-catalyzed episulfidation and the reaction proceeds stereoselectively as yy/z-addition e.g., the episulfidation reaction of trans-cyclooctene affords /r my-epithiocyclooctane (Scheme 10) <2003JA3871>. 

Sulfur dichloride was also used in the synthesis of 2,5-bis(trimethylsilyl)-EDOT 52, from which EDOT could be obtained by reaction with fluoride [123], The basis of the route is a zirconocene coupling generating zirconacyclopentadiene 51 from the reaction of two alkynes, linked with a 0(CH2)20 tether, with zirconocene dichloride (bis(cyclopentadienyl)zirconium(IV) dichloride). The zirconacycle reacted with sulfur dichloride generating the thiophene ring of 52 (Scheme 76). 

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