Phenyl selenenyl halides

As well as selenenyl halides, N-phenylselenosuccinimide (N-PSS) and N-phenyl-selenophthalimide (N-PSP) are widely used as powerful selenenylating reagents in organic synfhesis. N-PSS and N-PSP are conveniently synthesized by reaction of diphenyl diselenide with N-chlorosuccinimide and N-chlorophthalimide, respectively (Scheme 15.12) [39]. 

The first example of the use of the catalytic one-pot procedure described above, in which the deselenenylation occurs with substitution, is represented by the conversion of vinyl halides into a-alkoxy acetals [116]. This is illustrated in Scheme 38 in the case of -bromostyrene 235. The regioselective methoxy-selenenylation affords the a-bromo selenide 236, which undergoes a rapid solvolysis, through a selenium-stabilized carbocation to produce the selenide 237. Oxidation of this alkyl phenyl selenide with ammonium persulfate produces an oxygen stabilized carbocation, which affords the final product 238, and, at the same time, regenerates the selenenylating agent. 

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