Acylsulfenyl halides

Acylsulfenyl halides are formed by the reaction of N-bromosuccinimide or tert-butyl hypochlorite with thiocarboxylic acid O-trimethylsilyl esters164 (equation 172). Treatment of silyl carboxylates with triphenylphosphine dibromide gives the corresponding acyl bromide along with the silyl bromide165 (equation 173). It is also possible to convert silyl ethers to the alkyl bromide with this reagent165 or with a mixture of carbon tetrabromide and triphenylphosphine166. The mild nature and selectivity of the reaction is underscored by the conversion of the trimethylsiloxy /Mactam 83 to the bromide 84165 (equation 174). 

Heating 65, 68 (M=Zn, Cd R=CH3, tert-C H L=3,5-lutidine) gives metal sulfides in quantitative yields with the elimination of diacyl sulfides [249]. Treatment of mercury bis(thioacetate) with an aqueous solution of KOH gives mercury sulfide and potassium acetate [307]. Phenylmercury thiocarboxylates 70 react with AT-bromo- [148] and JV-iodo-succinimides [146] to give the corresponding acylsulfenyl halides (Scheme 5) (see Sect. 2.3.5). 

Scheme 12 Syntheses of acylsulfenyl halides using organostannyl thiocarboxylates...

The acylsulfenyl halides 153-155 are labile thermally and toward oxygen. The stabilities toward oxygen and heat decrease in the order X=Cl>Br>I, while the stability toward moisture decreases in the order X=I>Br>Cl. 

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