Bromothiocyanation of alkenes
Abstract
Treatment of alkenes with ‘thiocyanogen bromide’ prepared from equimolar amounts of bromine and thallium(I) thiocyanate in wet chloroform, gives moderate to high yields of vic-bromothiocyanates. The addition proceeds by an ionic mechanism involving nucleophilic attack of a bromide ion on an S-cyanothiiranium cation. Unlike vic-iodothiocyanates, the vic-bromothiocyanates are not readily isomerized to the corresponding vic-halogenoisothiocyanates.