THERMOLYSIS of sulphonyl azides involves the initial forma- tion of sulphonyl nitrenes. In aromatic substrates, mainly insertion-(sulphonanilides) and hydrogen abstraction-(sul- phonamides) products have been obtained.' y 2 The presence of electron-withdrawing substituents in the aromatic sub- strates facilitates the formation of N-sulphonyl- 1H- a~epines.~ In benzene, thermolysis of methanesulphonyl azide at 80 "C for 120 h gave only traces of N-mesylazepine ...