phenylthiyl radicals, and of 2-butene with triethylsilyl and ethylthiyl radicals have been generated and their ESR spectra recorded. The resulting radical adducts show the same ESR spectrum starting either from the cis or the trans isomer of the title compounds The existence of only one isomeric radical is consistent with the lack of stereospecificity in the elimination reaction of phenylthiyl radicals from