In the addition of sulfenyl halides

The addition of sulfenyl halides to 2-thianorbornenes such as (85) is analogous to bromination in that rearranged products are obtained, e.g.. 

Simple 1,2-additions to this compound have been observed123131132 also in other sulfenylation reactions, and in other electrophilic additions involving strongly bridged intermediates. Although these results have been interpreted as evidence that additions of sulfenyl halides to symmetrical alkenes do not involve open carbenium ions before the product-determining step, the different behavior observed in the case of 49 suggests123 that close proximity is necessary to have transannular participation of 7r-bonds, at least in additions of sulfenyl derivatives and of some other electrophiles carried out in the presence of efficient nucleophiles. 

An example of addition of sulfenyl halides to an alkyne is shown in Scheme 1928 where the initial trans adduct of 1,4-dichlorobut-2-yne is further transformed by treatment with base or aluminum amalgam. Another example involves boron trifluoride-catalyzed addition of an arenesulfenamide to alkynes in the presence of acetonitrile, giving (3-acetamidinovinyl sulfides (Scheme 20),29 which can be hydrolyzed to (3-keto phenyl sulfides.30... 

Further studies on the reaction of sulfenyl halides with alkenes established that the addition occurs in an anti fashion. In this manner, syn- and nh-/j-chloroalkyl aryl sulfides were prepared by addition of arylsulfenyl chlorides to (Z)- and ( )-butene16. 

Addition of a selenenyl halide to an alkyne takes a course analogous to that of the sulfenyl halide, as seen in the reaction of l,4-dichlorobut-2-yne with PhSeCl or PhSeBr (Scheme 19).28-62 Selenenyl halides also undergo facile addition to allenes with exclusive attack by selenium occurring at the central allenic carbon.63... 

Shortly after World War II, a research chemist at the Standard Oil Development Company (Esso) strolled into an oil additive laboratory and saw an interesting intermediate called perchloro-methyl mercaptan (CCI3SCI). A. F. Kittleson, spurred by visions of the trichloromethyl group in that then new miracle drug DDT, decided to try some reactions with the above described sulfenyl halide. 

J-Alkyl- or -arylthio amines were obtained by nucleophilic attack of an amine on episulfonium ions generated by reaction of sulfenyl halides or tetrafluoroborates with alkenes15-18. An effective azasulfenylation was also induced by dimethyl(methylthio)sulfonium tetrafluorobo-rate (DMTSF) in the presence of amines. With this latter reagent ammonia also adds to a double bond19. ant/ -Addition products are exclusively formed. 

Thiosulfonic S-esters3 are powerful sulfenylating reagents,4 more reactive than the commonly used disulfides, and more stable than the very reactive sulfenyl halides. In addition, they have found wide industrial applications as biologically active compounds or in polymer production.3 Their use, however, has been limited by the lack of easy and practical preparations. 

This reaction has been modified to use a sulfoxide as a synthetic equivalent of a sulfenyl halide. In addition, a procedure that involves the initial mixing of ethyl (methylthio)acetate and sulfuryl chloride, followed by the addition of aniline with one equivalent of proton sponge and final EtsN treatment can be used to prepare oxindole that is not accessible via the initial Gassman protocol. ... 

The disulfide (156) has proven to be a valuable and versatile intermediate. Treatment with bromine or chlorine resulted in the corresponding halomethylpenam in high yield (Kamiya et al., 1973), which on dissolution in dimethylformamide afforded an efficient conversion to the 3-halocephams 168 and 169, respectively. It was postulated that the initial product formed on treatment of 156 with the halogen was the highly reactive sulfenyl halide (170) which on addition to the olefin yielded the episulfonium ion (171) (see Scheme 5). The penicillins derived from 171 represented the kinetic products, whereas the corresponding thermo-... 

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