Evidence for 1,2-ketocarbenes in thermolysis of sodium o-halogenophenoxides and for benzothiirens in thermolysis of sodium o-bromobenzenethiolates

Abstract

Evidence for the intermediacy of a 1,2-ketocarbene in thermolysis of sodium o-bromophenoxide at 260° in alkyl benzenes to give dibenzo-p-dioxin is provided by trapping reactions with phenols, benzenethiols, and benzamide, benzoxiren being excluded by ¹³C FT n.m.r. experiments, in contrast to the conversion of sodium o-bromobenzenethiolate into thianthrene, similarly shown to proceed via benzothiiren.